Pho-mula for success: exploring the culinary science behind an exquisite bowl of pho

When someone declares where you can get “the best” particular dish in town, how do they really know? One day I asked myself this question and before I knew it, I was making daily visits to pho restaurants across three counties. I decided I was going to rank every single pho restaurant in town. How can someone say what the best is if they haven’t had it all, right? No rock left unturned – no nood left unslurped. Somewhere along the way I made this chart plotting every pho restaurant in Salt Lake, Utah, and Summit County.

You might know me as PhoKingSLC from Instagram where I documented this deep dive pho-rensic investigation day by day, bowl by bowl.

When I was working on ranking each restaurant, I tried to keep it simple. Evidently, this didn’t happen. This article details the reasoning behind whether a restaurant is placed closer to “Not phở me” or towards “Phở King Approved“.

I like to independently look at each component of a bowl. The way I see it, pho is made up of 4 components. Here’s what they are in order of importance:

1. The broth
2. The proteins
3. Herbs/veg/condiments
4. Noodz

Disclaimer: I don’t claim to be an expert in pho. One of my goals of this project was to learn more about my roots. The more I learn, the more I realize how deep this rabbit hole goes. Pho-ever.

The broth

The broth is the soul of pho, easily the most important component. Though chicken variants exist, pho broth is typically made from beef, onions/shallots, ginger, yellow rock sugar, fish sauce, and spices. The broth is where the flavor is and It’s what makes pho, pho. The very first thing I do when my bowl comes out is to take a sip of the broth. A great broth comes out piping hot and packed with oomph. It should be both beefy and seasoned, enjoyable before adding any condiments.

When it comes to the broth, I’m looking for two things. The first and most obvious is taste. I’m looking for something that would make my grandma jealous, a broth with body and depth that reinvigorates in a way that only pho can. The second is an often overlooked aspect: mouthfeel. It should have a silky texture that only comes from simmering for very long periods of time, often days. Thin, watery broths are a big no-no.

A semi-secret ingredient that gives pho broth both taste and mouthfeel is oxtail. Once regarded as scrap meat, oxtail has become a sort of premium specialty beef cut – much to the dismay of my bank account. Oxtail takes pho to the next level because it contains everything a broth needs to shine; beefiness, fat, and collagen. Admittedly, oxtail is very awkward to eat due to its odd shape. Even if you’re not interested in trying to figure out how to eat the damn thing, seeing oxtail on the menu is a very good sign. Any pho joint that offers oxtail almost certainly uses it to make their broth. Given its high price and relatively low frequency of being ordered, I see this as an indication that the restaurant is willing to spend the money to make a great bowl of pho. I don’t think it’s a coincidence that my top 3 restaurants (Rollz, Pho 33, and last but not least Pho 777) all serve oxtail. I didn’t even notice this until the end of the project. Other restaurants with some good ol’ oxtail include Pho 28, Pho Salt Lake, Asia Palace, and occasionally The Pearl.

Pro tip: if you’re not on a diet and want a richer broth, ask for nước béo (kinda pronounced like nook bell) aka fatty broth. The fat that accumulates at the top of a pho broth is usually skimmed off and discarded, but it contains deeply beefy flavor compounds that are not dissolvable in water. If you’ve never tried this before, there’s a whole new dimension of pho that you haven’t been introduced to.

Why does pho take so long to make? Because Pho QYU, that’s why

You’ll often see pho restaurants advertise the amount of hours their broth is simmered for. The reason pho broth is simmered for a prolonged amount of time is to convert collagen into gelatin in a process called partial dehydrolysis. This process requires heat and time. Collagen is the most abundant animal protein and makes up connective tissues – think of the inedible gummy parts of a steak or chicken wing. Gelatin, unlike collagen, is water soluble and gives the broth a velvety viscosity. This is important for avoiding a soup that is too thin and allows for the flavors of the broth to linger on your tongue. It’s a huge indicator of quality in pho.

I strongly suspect there’s pho joints out there that are taking shortcuts when it comes to making their broth. I suspect this because growing up, it’s a taste I’ve become familiar with. My parents were often too busy to cook and they took pho shortcuts of their own. Not everyone has the time to simmer a pot for the entire day. In Asian grocery stores, you can buy a premade pho base that comes in a powder or paste. These mixes don’t contain gelatin and produce a thin broth that tastes flat and artificial. Granted, this method can still be tasty when dressed up with fresh ingredients. It’s great for home cooking when you want something inexpensive, fast, and convenient – not so much for serving in a restaurant. I can’t undoubtedly prove that a restaurant uses a soup base without infiltrating their kitchen, but I had an idea of doing some testing to get some hints. I decided to put a restaurant in question directly up against my favorite 2 pho shops in Utah, Pho 777 and Pho 33.

I’m really overthinking this but stay with me here. Anything dissolved into water increases the amount of light that is refracted through it. Essentially the higher the refractivity, the more “stuff” that is dissolved into the broth. Because gelatin is dissolved into the broth, we can measure its relative amount by using a refractometer. This same method is sometimes used by ramen chefs to measure their broths for consistency.

Although gelatin increases refractivity, so will sugar, salt, and anything else that dissolves into water. This can create some limitations when trying to measure a specific solute. With ramen broth, refractivity is measured before salt and seasoning is added. High refractivity in an already seasoned broth could just mean the broth is very sweet or salty. It’s important to know that refractivity just gives us a clue to what might be going on. It only makes sense under the context of what the broth actually tastes like. In the end, taste is king.

My refractometer measures in Brix, a unit often used to measure sugar in honey or wine. To avoid confusion of what’s being measured, I came up with a new unit. I call it the Pho Quantitative Yumminess Unit or for short, Pho QYU. Low levels of Pho QYU suggest broths that are watery and bland. High Pho QYU indicates a broth with elevated amounts of solute. These broths are likely to be silky and flavorful.

I needed a frame of reference so I took periodic measurements of a broth I simmered over 24 hours at 94 ±2°C. I used about 3.75 lbs of beef bones in 4 quarts of water and refilled to volume as needed. I’ve found that around 2-3 Pho QYU is where the broth texture becomes noticeably more viscous than water. I’d say that before adding salt and sugar, 3-6 Pho QYU gives an ideal mouthfeel for pho. Not too watery, but not too thick.

So getting back to the point, I measured the Pho QYU of Pho 777, Pho 33, and a restaurant that I ranked on the lower end. Thankfully, the data supported my suspicions and all of this was only a moderate waste of time instead of an absolute waste of time. (Phew!) The broth at the mystery restaurant is notably bland without any body or depth. I measured a Pho QYU of 3.07 although this value is after salt, sugar, and other seasonings were already added by the restaurant. The true Pho QYU would be even lower.

It’s not my intention to trash on a local business, so this mystery restaurant will not be revealed.

Pho 33 has a higher Pho QYU than Pho 777, but I think this may be due to P33 having a higher amount of sugar. Both broths show signs of quality without shortcuts being taken.

The proteins

The second most important factor to a great bowl. A bowl of pho with great broth and mediocre meat will always beat a bowl with mediocre broth and fantastic meat. What I’m looking for is straightforward – tender and flavorful beef.

At a typical pho joint, you order your bowl by the cuts of meat. These can range from various cuts of steak, to meatballs, to tripe. One of the most popular options is called phở tái, which comes with thinly sliced rare beef that cooks in the broth. My favorite is phở chín. It comes with beef that was slow cooked in the broth for hours. With a few exceptions, I judged each restaurant by their phở tái chín since it includes both cuts.

In Vietnamese, tái and chín translate respectively to rare and cooked. They don’t necessarily refer to a specific cut of beef and the quality of beef can vary greatly between restaurants. Is the beef tender or is it cardboard?

For tái beef, most restaurants will use eye of round. This cut is why phở tái even exists; it’s one of the most lean cuts of beef and is very susceptible to overcooking. Serving rare beef to be cooked in hot pho broth is not a gimmick. People found that the best way to serve a normally tough and chewy cut was: 1) rare, to be cooked and eaten immediately, and 2) cut as thinly as possible. The best phở tái will instead use cuts like flank, much more tender. With phở tái you’ll run into one of 3 situations. In my opinion, here’s what they are from most preferable to least.

1. The restaurant uses more tender cuts and/or the beef is served slightly rare. Eye of round can be chewy when overcooked but it’s nice if the restaurant gives you the option of having it stay a bit rare.
2. The beef is served fully cooked, it will likely be chewy.
3. Your beef is fully cooked and is drastically curled or shriveled. The shriveling comes from the meat fibers tightly constricting, making the meat very tough to chew. This can happen if the beef was cut with the grain instead of against it. No bueno.

Note: If you want to look like a pro, order your rare beef on the side so you can cook it to your exact preference. Just know that depending on how often this is asked at the specific restaurant you’re at, you may or may not come off as a psycho.

For chín beef, it’s more simple. The beef in phở chín are typically semifatty cuts like chuck, brisket, or really any kind of roast. Most people know about pho broth being made from beef bones, but cuts of beef are thrown in as well. The beef simmers with the broth in a symbiotic relationship, a quid pro pho, if you will. The beef flavors the broth, and the broth slow cooks the beef. The meat from pho chin comes from one of these beef chunks and is thinly sliced before being served. I’m looking for something juicy, tender, and flavorful.

There’s many other proteins that you will commonly find in pho that I won’t go into here. I wanted to keep the rankings simple and relevant to what the typical person in Salt Lake would order.

Herbs, veg, condiments

All of the plentiful yet optional accoutrements including but not limited to; bean sprouts, lime, Thai basil, sliced pepper, hoisin sauce, and sriracha. The main thing I’m looking for here is freshness. Granted, I did my reviews in a desert state during the winter. Not exactly prime herb season.

It’s always a bonus for having a variety. I listed the standards, but you might also see some chili oil, chili sauce, or other herbs like culantro (Mexican coriander) and maybe even a perilla leaf.

Something I realized about myself during this project is how strongly I feel about the way the onions are cut. Ideally, the onions are cut into thin strands so that they can become homogeneous in shape with the noodles, much like the bean sprouts. This makes the eating process go smoothly. If onions are overly thick, it’s not the hugest deal. The thing that irks me is when the onions are cut into rings. Why? Why would anyone do this? The onions and noodles become tangled into each other and it becomes a knotty mess. It almost as if there’s a boy scout in the kitchen trying to earn dual merit badges in knot tying and trolling.

The noods

Noods are vital, but most people are surprised when I tell them that when it comes to pho the noodles are the least important component. Why? Glad you asked. All the pho noodles in Utah are nearly indistinguishable from each other.

The noodles in pho are the same noodles in pad Thai. They’re made from rice. Making rice noodles requires specialized machinery and equipment. Rice noodles are very hard to work with because there’s no gluten to keep the dough together. Mess up your rice noodles just slightly, and your noods will struggle to maintain any semblance of structure. Though rice noodles have existed for thousands of years, it wasn’t until after the industrial revolution that they were able to be made consistently in large amounts. Virtually no one makes rice noodles themselves – it’s left to the professionals.

In Vietnam, these noodles are available fresh and daily from a specialty shop where both restaurants and home cooks alike will source their pho noods from. In this case, the noodles are a very important aspect to judge. In America this just isn’t an option for us. As far as I know, no such rice noodle specialty shop exists in Utah. All pho restaurants use the same quality noodles that come from the same handful of manufacturers. When I make pho, I like to tell myself that the brand of noodles I buy taste better than the other ones. But if I’m being honest? It’s very difficult to tell the difference and all store-bought pho noodles are nearly identical. Judging pho on the noodles would be like ranking restaurants on whether they use Heinz or Hunt’s ketchup.

The noodles are practically never made in-house, much like how most burger places don’t make their own buns. There are pho restaurants in California that advertise house-made noodles, but I see this as a gimmick. Since pasta and ramen noodles have gluten, being handmade makes sense in certain cases. But for pho and rice noodles? Always a bad idea.

I did, however, take it into account if the noodles were over or under cooked.

Okay, so how does it all come together? How do I even eat this stuff anyways?

How pho is eaten loosely ties into how I review bowls since the way you eat can drastically change your experience. I’m often asked what’s the “correct” or “authentic” way to eat pho. I haven’t found any information online that I feel is a complete answer. I’ll use this opportunity to give my take.

In short, the beautiful thing about pho is that you can make it into whatever you want. The proper way to eat pho is whatever way lets you enjoy your bowl the most. You can slurp up your noods with a boba straw for all I care. You do you, bro.

If you were to take 10 Vietnamese people and watch how they eat pho, it’s likely that no two would eat in the exact same way. I don’t think pho has been around long enough for hard rules to become established. Pho didn’t exist until the early 1900’s in Northern Vietnam. The vastly different Southern variation that’s become popular around the world wasn’t widespread in Vietnam until the mid-late 1950’s after the 1954 Geneva Conference allowed for a large migration of Northerners into the South. There are no rules here. It’s the noodle soup wild West and there ain’t no sheriff in town. At the end of the day, anything that’s not served in your bowl is an optional addition and you can do whatever you want.

If that’s not good enough for you, I have suggestions on do’s and don’ts if you’re worried about making a pho faux pas and getting arrested by a pho-lice officer.

As a child I was berated for the way I ate pho for seemingly purposeless reasons like eating with only one hand, for example. Nowadays, the eating habits of my parents are ingrained into me whether I like it or not. Though in hindsight, I’m realizing that there was intent behind the way they ate – it’s a way that lets me get everything I want out of my bowl. For what it’s worth, here’s how I eat pho.

1. Chopsticks in my dominant hand, soup spoon in the other. By the way, there’s no shame in using a fork instead of chop sticks. The very first thing I do is use the spoon to taste the broth and determine what I need to add. When I’m deciding where to rank a bowl I take much more sips so that I can be confident in where I think the broth stands. For regular eating you shouldn’t need more than a single sip or two. If the broth is sweet or highly seasoned I’ll add more lime than I usually would. The acidity from the lime compliments these flavors and will “brighten” up your bowl. I always add a bit of sprouts and rip up some herbs into the broth. The amounts just depends on my mood.
   • In my opinion, ripping your herbs is a must. The tears in the leaves allow the herb’s flavors to steep into your broth much more easily. As you’re ripping, hopefully you’re slapped across the face with an herby aroma. This indicates that the herbs are fresh. I also like doing this because I can avoid eating an entire leaf – too overwhelming of a flavor.
2. I’ll give the bowl a bit of a mix and loosen up the noodles. I’ll give the broth another couple of sips before I make a decision. If I think the broth is tasty and can stand on its own feet, I’ll move onto the next step. Frankly, if I think the broth sucks I’ll add some hoisin sauce or sriracha.
   • Adding sauces into your bowl rather than using them for dipping, especially with sriracha or chili oil, can be a controversial move that will make pho snobs cringe. In my opinion it’s really not that big of a deal. Though admittedly, I’m one of these pho snobs. I’ll explain the reasoning – Let’s say you were to drench sauce into two different side-by-side bowls, one awesome bowl and one crappy bowl. They would taste almost identical, like sauce. Pho broth is delicate. It takes very little to overpower its flavor. I add condiments only if the broth is bland or if the restaurant has some bomb chili oil.
3. This is when the actual eating part happens. I’ll take a bit of noods and place them into my soup spoon. I sink the spoon into the broth to make a sort of “mini-bowl” of both noods and soup. I like to eat pho this way because the broth is where all the flavor is and I want to get some in every bite. It also makes less of a mess. Occasionally I’ll use my chopsticks to bring noods directly to my mouth, but I primarily eat from the spoon.
4. Dipping time! At some point before this step I prepared a dipping dish. I’ll grab some beef and lightly dip it into whatever combination of sauces I was feeling that day. It’s usually hoisin and sriracha, maybe with some lime and chili oil if I’m feeling freaky. Sometimes I eat this piece of meat by itself, and sometimes I place it on top of the mini-bowl in my spoon. There’s also times that I don’t bother dipping at all. It just depends on what I feel like eating at that given moment.
5. Lather, rinse, and repeat steps 3 and 4 until your soul is revitalized. If your bowl is empty and you still aren’t fully rejuvenated, order another and start again at step 1.

Again, I feel that it’s important to stress that my way isn’t necessarily the best or only way. It’s just what works for me.

Editor’s note: this is part one in a two part series. Stay tuned for Brandon’s full ranking of the very best pho restaurants in Salt Lake City.

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Brandon "Pho King" Luong

Hey, I’m Brandon! I’m also known as the noodle whisperer, the broth sommelier, but most often as the Pho King. I grew up in the Salt Lake Valley, but spent summers in Southern California — debatably the Vietnamese food capital of America. I’ve worked in multiple restaurants, but also have a science background. I’ve even had a brief stint with NASA! I love food, dad jokes, and overthinking. I guess all of this rambling was just a natural progression.

You can find more of my blabberings on Instagram.

www.instagram.com/phokingslc/