Why It Works
- Toasting the aromatics before making the curry paste deepens their flavors and makes them softer and easier to pound.
- Using a real mortar and pestle along with a pinch of salt extracts the most flavor from the aromatics to make the best curry paste.
Rich, creamy, and packed with uncompromising flavor from a slew of aromatics and shrimp paste, this classic Northern Thai soup combines tender braised chicken in a coconut-y curry broth with boiled and fried noodles. Our version is the real deal, straight from the streets of Chiang Mai.
"So that's what it's supposed to taste like," was a thought that went through my head repeatedly during my months long stint in Asia. It happened with Peking duck, and with fried soup dumplings. It happened with fiery Sichuan food and spice-packed Chinese Muslim food in Xi'an. And it happened the first time I ate khao soi—the rich Thai coconut-curry noodle soup—in Chiang Mai.
Having learned and loved the flavors of these regions through their interpretations back home in the U.S., I knew that I was tasting them through the lens of cooks who had adapted the recipes for themselves or for their customers. But tasting the real thing in situ lets you really understand its importance.
Of course, that's all a load of B.S. Even in Chiang Mai, there are hundreds of variations of khao soi—and we're talking just the laksa-inflected Thai version here, not any of the other variants, which differ as widely as anything in the U.S. does. That said, the best khao sois I had shared some common traits: impeccably fresh and bouncy egg noodles; a richly textured broth so intense that it was served only in small quantities; layer upon layer of flavor made by picking the right aromatics and not being lazy with their treatment. (Woe betide the Thai cook who opts for a food processor instead of a mortar and pestle to make his curry paste!)
I have already talked about khao soi, so rather than coming up with a whole new description, please allow myself to quote...myself:
Northern Thailand's de facto signature dish, a coconut and curry-flavored noodle soup, is also one of its most regionally incongruous. Wet curry pastes, made by pounding roots, rhizomes, seeds, spices, herbs, and various fermented seafood products, don't feature heavily into Northern Thai cuisine, nor does coconut cream, the way it does in the curries of Central or Southern Thai. Stretchy, eggy, Chinese wheat noodles are also not particularly common.
As Andy Ricker pointed out in this New York Times piece, it's "exotic without being weird and, most important, completely delicious." It's the kind of dish everybody can love.
Often when I approach adapting a foreign recipe for a largely American audience, I do what those American-Thai restaurants do: I spend a lot of time working out how to replace tricky-to-find ingredients or how to adapt flavors to be more suitable to a Western palate.
This time, I'm doing no such thing. In fact, I'm dead sick and tired of the toned-down khao soi you get here. If you're looking for easily-made-out-of-stuff-I-can-find-at-my-local-Safeway, then move along: this is not the recipe for you.
This is the recipe for folks who are willing to scour the back streets in search of makrut limes. Folks who will settle for nothing but fresh turmeric. Folks who'd rather pound their own heads flat in the bottom of a solid granite Thai pok pok than pull out the food processor. Folks who want to get as damn close to Chiang Mai as they can without leaving their homes—or at least their greater metropolitan area. (You may have to travel some lengths to find that black cardamom.)
Ready? Got your passport with you? And...takeoff!
Khao soi is essentially a curry soup, and as with any Thai curry, making the paste properly is the most important step. Similar in profile to muslim-influenced Massaman curry pastes, khao soi paste is made with a combination of moist aromatics and dry spices. I use a mixture of shallots (the small Thai variety if you can get them, or just the smallest Western shallots you can find if not), garlic, lemongrass, makrut lime zest or leaves, fresh turmeric, ginger, and cilantro root for the moist aromatics. As I discovered when I was working on my Thai-style grilled chicken (gai yang) recipe, the hearty thick ends of cilantro stems are just as good—if not better—then actual cilantro root, so I used that here.
For the dry aromatics, I use a spoonful of coriander seed and some black cardamom. Now, normally, I'd toast those spices whole, but in this case, we've got a little trick up our sleeve that'll preclude the need for toasting and deliver better flavor in the end: Roasting all of the aromatics in a foil pouch until charred.
This accomplishes two goals. First, it helps develop an extra layer of flavor as aromatic compounds within the spices break down into smaller parts and reassemble into hundreds of new ones in a process known as the maillard reaction. Secondly, it softens up the vegetables and begins the process of releasing their aromatics. This is a godsend when I tell you what's coming next:
Pounding, pounding, and more pounding. I've made khao soi and other curries in the past side-by-side with spices pounded in a mortar and pestle (a heavy-duty granite number is a good choice) and pulverized in a food processor and the flavor simply doesn't compare. By pounding spices, you rupture their cells, releasing the aromatic compounds within. Keep pounding and you eventually cause them to mix together with other compounds, triggering chemical reactions that build in layers of complex flavor.
This simply doesn't happen in a food processor, which, rather than pounding, slices aromatics and spices. Not only that, but the violent action of a food processor can actually create strong fat and water emulsions that prevent the flavorful compounds that do get released from interacting with each other in a meaningful way (or reaching your mouth, for that matter).
Have you ever had a Thai curry so good that it made you want to leap up in your seat with joy? Take a peek into that kitchen, and I guarantee you'll spot the one buff prep cook whose job it is to pound that paste.
Pounding curry paste for khao soi is no walk in the park either. If you ever have to ask "do you think this is pounded enough?" the answer is always no. Pound, pound, and pound again until you can pound no more. Then we're ready to move on.
Once the paste is done, I stir in a big spoonful of shrimp paste—another Thai ingredient that's often omitted in Westernized versions of the soup.
Believe it or not, the most difficult part is over. Everything else is smooth sailing from here.
Khao soi is a coconut-based curry, and for the very best results, you'll want to squeeze your coconut fresh.
Grated mature coconut, when squeezed in a clean dish towel, releases a surprisingly voluminous amount of creamy milk. Unfortunately, it's nearly impossible to find good mature coconut in the U.S., much less a place that'll grate it for you. Fortunately, canned coconut milk actually does a damn good job on its own, so I don't really consider it a compromise.*
*You sticklers are welcome to find your own coconuts if you'd like. And if you want to really get hardcore, grate it by hand on one of those full-body-contact coconut graters instead of a machine.
The coconut milk is essential for two things. Not only does it provide flavorful liquid in which to cook your chicken, it also provides fat to bloom your curry paste. When you scoop off the top layer of fat-rich coconut milk and cook it down in a wok, the liquid phase eventually evaporates, leaving behind clear, pure coconut fat, along with some browning proteins and carbs. Add your curry paste to that fat and cook it until aromatic, and you've gone another step towards compounding your flavor.
Once the curry paste is bloomed, I slowly add the remaining coconut milk and bring it to a simmer.
At this stage, many Thai cooks would then add a raw chicken, along with some water, before letting it simmer until the chicken is tender. This works in Thailand mainly because the chickens look like this:
They're skinny, scrappy, and packed with flavor, albeit relatively scrawny and tough. Even in the short period of time it takes to cook the meat, the broth picks up enough rich chicken flavor to carry the dish.
On the other hand, I prefer the meatier, more tender meat that our Western chickens have—even if I could get a Thai chicken to flavor my soup, I'd still throw in a few Western chicken legs to serve with the finished dish. To get the best of both worlds, I use regular chicken legs, but instead of plain water, I use chicken stock for the broth base.
As it cooks, the broth should get thicker and break a little, with tiny droplets of flavorful spiced chicken fat pooling on the surface. It should also smell awesome.
Last element: the noodles. In Chiang Mai, khao soi invariably comes with yellow, stretchy, flat egg noodles about 1/4-inch wide and 1/8th-inch thick. Think fettuccine or linguini, if you will. In the West, you often see khao soi served with lo mein noodles, or even fat rice noodles. But if you take a quick peek at our Chinese noodle style guide, you'd know that wide wonton noodles are what you're looking for.
I don't know what wacky, crazed mind came up with the idea of serving the noodles two ways in the soup, but khao soi gets a nest of crisply fried noodles perched on top of the slick, boiled noodles underneath.
I'm never one to say no to extra fried.
For the boiled noodles, the only trick to remember is not to overcook them. Like many other Asian noodle dishes (see: ramen), the noodles should arrive at the table almost undercooked so that they'll be the perfect stretchy-chewy consistency as they continue to cook in the hot broth.
Putting It Together
Ladies and gentlemen, please put your seat-backs in the upright position and stow your tray tables. We're about to come in for a landing, and we're coming in hot.
Start with your noodles, add some braised chicken and a few ladles full of hot broth, and finish it off with the fried noodles. Serve it with lime wedges, pickled Chinese mustard root, and sliced shallots. Welcome to Northern Thailand. It's nice here. I hope you'll stick around for a while.
- 1 small bunch cilantro stems, leaves and thin stems reserved for another use
- 2 whole small shallots, peeled and sliced into quarters
- 4 whole cloves garlic
- 1 (1-inch) knob fresh turmeric, roughly chopped
- 2 thin slices fresh ginger
- 1 stalk lemongrass, bottom 4 inches only, roughly chopped
- 1 whole dried Thai bird chile (or 1 whole chile de arbol), more or less to taste
- 1 teaspoon makrut lime zest, or 2 whole makrut lime leaves (see note)
- 1 teaspoon whole coriander seed
- 6 pods Thai black cardamom or 1 pod green cardamom, inner seeds only
- Kosher salt
- 1 1/2 tablespoons Thai shrimp paste
- 1 cup vegetable or canola oil
- 1 pound fresh Chinese-style egg noodles, divided
- 2 (15-ounce) cans coconut milk, or 2 cups fresh coconut milk (do not shake)
- 1 cup homemade or store-bought low-sodium chicken stock
- 2 tablespoons palm sugar (see note)
- 4 chicken legs, split into drumsticks and thighs
- Fish sauce, to taste
- Sliced shallots, lime wedges, and pickled Chinese mustard greens (see note), for serving
Place cilantro stems, shallots, garlic, turmeric, ginger, lemongrass, chile, lime zest, coriander seed, and cardamom in the center of a 12- by 12-inch square of heavy-duty aluminum foil. Gather up edges to make a tight pouch. Place pouch directly over the flame of a gas burner and cook, turning occasionally, until aromatic and wisps of smoke begin to rise, about 8 minutes. If no gas burner is available, place the pouch in the bottom of a wok or cast iron skillet and heat over high heat, turning occasionally, until smoky, about 10 minutes. Allow contents to cool slightly and transfer to a large mortar and pestle.
Add a large pinch of salt to the aromatics. Pound until a very fine paste is formed, about 10 minutes. Add shrimp paste and pound to incorporate. Set curry paste mixture aside.
Separate out 1/4 of the noodles (enough noodles to make a crispy fried-noodle topping for 4 bowls) and set the remaining noodles aside. Heat vegetable oil in a large wok over high heat until shimmering. Working in batches, add noodles to oil and fry, stirring and flipping until golden brown and crisp. Transfer to a paper towel-lined plate. Season with salt and set aside.
Discard all but 1 tablespoon oil from wok. Using a spoon, skim 2 tablespoons of creamy fat off the top of the coconut milk and add to the wok. Heat wok over high heat and cook, stirring constantly, until coconut milk breaks and oil begins to lightly smoke, about 2 minutes. Add curry paste mixture and cook, stirring and smearing the paste into the oil, until aromatic, about 45 seconds.
Slowly whisk in the coconut milk, followed by the chicken stock and palm sugar. Add chicken legs and bring to a simmer. Cook, turning chicken occasionally, until chicken is tender and broth is very flavorful, about 30 minutes. Season to taste with fish sauce.
Bring a pot of salted water to a boil. Add remaining uncooked noodles and cook until al dente, about 1 minute. Drain noodles and divide between four warmed bowls. Top noodles with two pieces of chicken. Divide broth evenly between bowls. Top with fried noodles and serve immediately with sliced shallots, lime wedges, and pickled mustard greens on the side.
Makrut lime and palm sugar can be found in Asian specialty grocers or some high-end supermarkets. If palm sugar can't be found, brown sugar can be used in its place. If makrut lime can't be found, omit. Pickled mustard greens can be found in most Chinese markets.