The Food Lab: How to Make Thai-Style Grilled Chicken (Gai Yang)

The Food Lab

Unraveling the mysteries of home cooking through science.

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Sweet, savory, and intensely aromatic Thai-style grilled chicken. [Photographs: J. Kenji López-Alt. Video: Vicky Wasik]

Remember that scene at the end of the third season of Lost, when you realize that the whole episode has been flash-forwards instead of flashbacks, and we end up on a bearded, scraggly Jack in tears, as he screams We have to go back! at Kate's cold taillights as they fade into the night?

That's how I've felt every single time I've eaten Thai food since leaving Thailand after a short visit over half a decade ago. Every time I smell sweet meat on the grill, the aroma of charred lemongrass or coriander root, I think, I'm tired of lying to myself: I was never supposed to leave.

Thailand is the single greatest food destination in the world. Walk the streets, take in the smells, point at what you want to eat, and for a few baht—the equivalent of a quarter or a half dollar—you'll put into your mouth something indescribably delicious, a bite with flavors you could never have even dreamed existed before experiencing them. Walk a few more yards, and the whole process repeats itself. You can walk around Bangkok or Chiang Mai or northeast Thailand for days eating every single dish that strikes your fancy, never spend more than $5 in a day, and never eat the same thing twice.

You could never eat the same thing twice, but you'd most likely want to make a few exceptions. Those awesome hot-fried, chili-stuffed omelettes. Little fermented Lao sausages flavored with kaffir lime and lemongrass. Grilled pork neck served with a dried-chili dipping sauce. And, of course, gai yang.

Thai cooks are experts at grilling all manner of meats, but nowhere does that proficiency shine more brightly than with chicken. Gai yang originated in Isan, Thailand's northeastern region, populated largely by Thai Lao people, but it's one of those dishes that are so good, they've spread to all corners of the country. Characterized by crisp, golden skin, coated in a richly charred marinade of toasted spices and herbs seasoned with fish sauce and sugar, the chicken is butterflied, flattened, and threaded onto bamboo skewers before being slowly grilled over charcoal. It's tasty enough on its own, but when dipped into a sweet and spicy chili sauce, it becomes mind-blowingly delicious.

Ever since tasting it for the first time, I've been trying to re-create some of that magic at home. This year, I finally nailed it.

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Gai yang my wife and I just ate from a market in Nong Khai, on the northeastern Thai–Lao border.

Ironically, I finally did make it back to Thailand this summer. In fact, as you're reading this, my wife and I are poking through the markets of Nong Khai, our fingers dripping in gai yang juice. And, as much as I wish I could bring all y'all with me, I'll have to settle for the next best thing and show you how to make it at home instead.

The Marinade

Marinade ingredients for gai yang vary widely, but there are always a few key players. Coriander root, with its mild, almost soapy flavor, forms the backbone. Plenty of garlic is also a prerequisite for admission, as is a good amount of palm sugar. White pepper, fish sauce, and soy sauce round it out. Many recipes go on from there, with ingredients like lemongrass, turmeric, or even coconut milk. After testing a number of these ingredients, I found I preferred mine simpler and decided to stick with the base ingredients, along with some lemongrass when I'm feeling particularly feisty.

One of the major problems, however, is that cilantro root is hard to come by. You can cheat your way there by using a dab of green curry paste—most are based on cilantro root—but then you end up with all kinds of unwanted flavors (chilies, in particular).

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Instead, I found that incorporating the fat, robust ends of cilantro stalks provided a flavor that was close enough to the real deal to satisfy me.

Palm sugar can also be a little difficult to track down. Fortunately, light brown sugar works just as well in its place.

Next question: Traditionally, the spice blend is prepared by pounding the ingredients with a mortar and pestle until a rough paste is formed. Would a food processor work just as well?

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I grilled up a couple batches of chicken side by side with marinades that differed only in how they were puréed. The difference turned out to be very subtle. While ingredients pounded with a mortar and pestle tend to release more flavor, particularly when you pound them with a bit of salt (read up more on that science in this piece about guacamole), once the chicken is actually grilled, those subtleties are lost.

I'll stick with pounding for spice/herb pastes that are served raw, and break out the food processor for those that will be cooked.

Marinating Time

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And what about the length of time the chicken spends marinating before grilling?

The vast majority of marinade ingredients—pretty much any of the large, aromatic molecules—will not penetrate very far into a piece of meat, no matter how long you marinate it for. A millimeter per day of marinating is about average.

But there are exceptions. Salt, in particular, is quite adept at making its way into a piece of meat. It does this by first dissolving a muscle protein called myosin. This causes the meat fibers to loosen up, allowing them to take in a bit of liquid. Salt comes along for the ride. What's more, once those fibers have loosened, they tend to stay looser even when cooked, which means that you can expect meat soaked in a salty marinade to retain more juices.

If you've read up on brining and dry brining, you already know all of this, as the process is identical.

When both are tasted side by side, chicken marinated for a few hours has more flavor and is juicier than chicken placed directly on the grill with no marinating time. Let it go for a night or two, and you'll be doing even better. And, because gai yang uses a nonacidic marinade (unlike, say, the yogurt-based marinade for tandoori chicken), you don't have to worry about the meat chemically "cooking" or turning chalky and dry.

This is one of those rare cases in which longer marinating actually is better, which means you can prepare the marinade and put the chicken in it on Thursday, then forget about it until Saturday. Procrastinators and planners, rejoice!

Grilling

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With my marinade out of the way, it was time to focus a bit more on the actual cooking process. As with all whole chicken recipes, we've got a few hurdles to tackle.

First off, there's the problem of breast meat and leg meat: Breasts are best when cooked to between 145 and 160°F (63 and 71°C). Any higher, and they end up as dry and crumbly as an IKEA particleboard bookcase.* Legs, on the other hand, with their high proportion of slow-twitch, heavy-use muscles, are better when cooked past 165°F (74°C).

* Having recently tried to disassemble and reassemble a few such bookshelves, I am keenly aware of their crumbling capacity. Also, do not listen to what the USDA says about cooking chicken to 165°F. So long as it is held and rested properly, chicken cooked to 150°F (66°C) or even lower is perfectly safe.

There's also the issue of getting the skin to crisp without burning, and timing it so that the skin reaches optimum crispness just as the meat finishes cooking.

The solution? It's something that the Thai already know: butterflying.

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Butterflying (a.k.a. spatchcocking) a chicken has become my go-to method not just for the grill, but for the oven as well. You know how in every single episode of Captain Planet, the kids try to solve the problems on their own, fail, and finally give in and call up Captain Planet, who puts everything right in moments?

Spatchcocking is your chicken's Captain Planet. By cutting out the backbone of the chicken and flattening it, you solve all of your problems in one fell swoop.

A butterflied chicken is thinner around its legs, which means that those thighs and drumsticks cook faster, ending up above 165°F by the time the breasts reach a juicy 150°F.

A butterflied bird also has all of its skin on one side, in more or less a single plane. This makes crisping it evenly much easier, and, with plenty of space for rendering fat to escape, it gets crisper than it ever could were the bird left whole. This flat shape also makes it easier to maneuver and flip as it cooks on the grill.

In the past, I've recommended threading whole butterflied chickens with skewers, in order to get them to stay flat as they grill.

This works well for little grilled Cornish hens or diminutive Thai chickens, but, in all honesty, full-sized, big, fat American chickens are a little cumbersome.

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I've taken to splitting them in half down the breast. In fact, you could even break them down further into individual breast halves and legs, but I find that at that stage, you actually start to lose more juices than you'd want to from all of the cut surfaces, not to mention more pieces on the grill = more fiddling come flipping time.

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In Thailand, the chicken or chicken pieces are secured clothespin-style with pieces of split bamboo. At home, I secure the flattened and split chickens with two skewers each, which makes them super simple to maneuver.

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For the cooking process, I found that the technique I developed for standard grilled chicken worked wonderfully well. It incorporates a relatively slow cook (for even cooking and maximum juiciness), followed by a quick sear to crisp up the skin.

Here's how it goes.

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You start out with a full chimney of coals. I'm using lump charcoal here, but briquettes would work just fine for a long, slow cook like this one.

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You want to arrange the coals in a two-level fire, in which all of the coals are banked up against one side of the coal grate and the other is left coal-free. (If you're using a gas grill, just set half of the burners to high and leave the others off.)

This creates a zone for indirect cooking on the cooler side.

This is where the chicken goes, with the legs closer to the coals, just to ensure that they cook faster than the breasts.

With the chicken on the grill and the coals arranged, cover the grill and cook the chicken, checking it every so often to ensure that it's not singeing or burning. Those little wing tips tend to go first. Little foil shields can help if it looks like anything is burning.

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Check those tips!

With a plain, un-marinated grilled chicken, I'd cook it on the cool side until it hit around 110°F (43°C), then transfer it over to the hot side to finish cooking for a further 10 minutes or so. I tried that with my gai yang and ended up with chicken skin that was burned to black cinders by the time the meat had finished cooking. The sugar in the marinade means that the chicken is extra prone to burning.

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Instead, I just fiddled with that timing, letting the breasts cook to 140°F—the legs end up around 160°F at this point.

And if you're doing everything right, then the aroma of smoky grilled chicken and spices should be drawing a good crowd of spectators by now.

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Yup, it's working.

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With the meat cooked through, flip the chicken over so that it's over the hotter side of the fire. If your fire is still burning very hot, you'll want to cook around the middle of the grill rather than all the way over to the other side. Keep a close eye on the chicken at this stage. A few black spots are good—desirable, actually—but there should still be plenty of deeply burnished, crisp skin showing.

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Once it's cooked, it's best to let the chicken rest for a few moments. As with a steak, resting will directly affect the amount of juice a cooked chicken retains once you cut into it and start eating.

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The final benefit of dealing with spatchcocked birds: They are much easier to carve. Just split the legs off the breasts, separate the drumsticks from the thighs, and split the breasts in half crosswise.

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The chicken is great on its own (and best eaten utensil-free), but it's even better with a good sauce. I always have a large batch of this sweet chili sauce in a container in my fridge. Unlike the jarred stuff, it has some real heat to it from fresh chilies, along with the fresh aroma of lime juice and the savory background of fish sauce.

Can't find fresh chilies, or want something with a smokier, deeper heat? Check out this dried-chili sauce from our resident queen of Thai, Leela Punyaratabandhu.

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I did say that this is best eaten with your fingers, right?

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That crisp skin, with the pungent heat of white pepper and the aroma of coriander and fish sauce, puts me right back there in the middle of an Isan side street. The only thing missing is the cheap plastic chairs and cold beer to wash it down.