Why It Works
- Combining a small amount of coconut oil with coconut milk ensures that the mixture “breaks” during cooking, so that the curry paste fries in coconut oil, drawing out its intense aroma.
- Coconut milk and palm sugar create subtle background sweetness that doesn’t take away from the spicy and savory profile of the curry.
Gaeng khiao waan gai, or green curry with chicken, is one of the most well-known and popular Thai curries in the world. A rich coconut milk-based curry, part of its crowd-pleasing nature is its balance: it’s spicy, but not too spicy; it’s sweet, but not too sweet; and the richness of the coconut milk pairs well with the relative leanness of chicken meat. The curry takes its name from the green chiles used to make prik gaeng khiao waan, the curry paste that forms its base, which also contains fresh aromatics, like lemongrass, galangal, garlic, and shallots, along with dried spices and shrimp paste. (The curry paste is fundamentally identical to the red curry paste, prik gaeng phet, used to make red curry, or gaeng phet, aside from the fact that it uses green chiles instead of dried red chiles.)
Like many Thai dishes, there’s a lot of speculation about its origins. Hanuman Aspler, a scholar of Thai food and one of my mentors, has noted that green curry is a relatively new addition to Thai cuisine, one that likely originated in the kitchens of the Thai aristocracy sometime during the 1920s. In his examination of historic Thai cookbooks, Aspler found few if any mentions of green curry, just red curry. And although there’s no definite answer as to why green chiles came to be used in place of red chiles to make green curry paste, there is speculation that the substitution came about due to the influence of Indian-style curries.
However, there's a lot of debate in both historical and current cookbooks, as well as in many articles, about how green curry should be seasoned. Many people look at the curry’s name and believe the curry should be quite sweet, which they accomplish by adding a lot of sugar, and quite green, which they accomplish by blending things like cilantro leaves and spinach leaves into the curry paste, as “khiao” means green and “waan” means sweet. But, as Hanuman explains, “khiao waan” is based instead on the words “aawn waan,” which means a pastel green color—it has nothing to do with sweetness—and since this curry is essentially a gaeng phet (red curry), its flavor profile should follow suit: it should be assertively savory and spicy thanks to the curry paste and a generous splash of fish sauce, with just a hint of background sweetness coming from palm sugar and coconut milk.
The dish itself comes together very quickly—provided you’ve made the prik gaeng khiao waan ahead of time, or you’re using a store-bought curry paste—and follows the standard cooking procedure for most coconut milk-based curries. Curry paste and coconut milk are cooked down until the water content of both has evaporated, causing the coconut milk emulsion to break or “crack,” with fat separating from the solids. At this point the paste begins to fry in the coconut oil, intensifying the fat-soluble volatile aromas of the chiles, dried spices, and fresh aromatics. This process deepens the flavors of the curry paste and carries them through into the finished dish.
After seasoning with fish sauce and palm sugar, chicken thigh pieces and floral makrut lime leaves are added, along with more coconut milk that has been thinned out with water, and the curry is brought to a simmer. This thinned coconut milk mixture mimics the texture of hang gati, the “tail,” or second or third pressing of coconut milk, which is much lighter and subtly flavored compared to the rich and thick hua gati, or “head” of coconut milk (also sometimes referred to as coconut cream) that’s “cracked” or broken in the first frying step of the curry’s preparation. Once the chicken is just cooked through, small Thai apple eggplants are added to the mix. The eggplants are crisp and slightly bitter, and along with the tender chicken, they provide textural contrast and a little respite from the heat and punch of the saucy curry. A handful of sweet (a.k.a. Thai) basil leaves are stirred in at the last minute, and the dish is garnished with finely sliced makrut lime leaves.
This is a thick, rich, green curry that can be served as part of a larger meal, and it pairs especially well with cooked jasmine rice, a fried fish or omelette, a sour and spicy soup like tom yam, or a simple stir-fry like galam plee pad nam pla (stir-fried cabbage with fish sauce and garlic).
- 1 1/2 cups (355ml) full-fat coconut milk, such as Aroy-D, divided (see note)
- 10 fresh or frozen makrut lime leaves, divided
- 2 tablespoons (30ml) virgin coconut oil
- 4 ounces (1/2 cup; 115g) homemade or store-bought green curry paste
- 1 tablespoon plus 2 teaspoons (35g) palm sugar
- 3 tablespoons (45ml) fish sauce
- 1 pound (450g) boneless skinless chicken thighs, cut into 2-inch pieces
- Kosher salt
- 5 Thai eggplants (about 5 1/4 ounces; 150g total), stemmed, quartered, and placed in a small bowl of water (see note)
- 1 packed cup (about 1 ounce; 30g) fresh sweet basil leaves (a.k.a. Thai basil)
- Cooked jasmine rice, for serving
In a small bowl, whisk together 1/2 cup (120ml) coconut milk and 1/2 cup (120ml) water; set thinned coconut milk mixture aside. Remove and discard the mid-rib from the makrut lime leaves; set 8 of the leaves aside. Stack remaining 2 makrut lime leaves, fold in half widthwise, then slice into hair-thin strips; set aside separately.
In a 3-quart saucepan, combine coconut oil with 1/2 cup (120ml) coconut milk and bring to a simmer over medium heat. Cook, stirring often with a rubber spatula, until thickened slightly, about 1 minute.
Add curry paste, stir vigorously to combine, and use a rubber spatula to scrape sides of the saucepan to fully incorporate paste. Raise heat to medium-high and cook, stirring and scraping constantly until paste mixture begins to spit (which indicates that water content has been cooked off, and mixture has begun to fry in coconut oil), about 1 minute. Lower heat back to medium, and continue to cook while gradually adding remaining 1/2 cup (120ml) coconut milk in 2-tablespoon (30ml) increments, until paste darkens slightly and the fat begins to separate from curry paste, 5 to 6 minutes.
Add fish sauce and palm sugar, and stir until palm sugar is fully dissolved, about 30 seconds. Lightly season chicken on all sides with salt, add to saucepan with reserved whole makrut lime leaves, and stir to evenly coat with curry paste mixture. Add reserved thinned coconut milk mixture and bring to a simmer. Cook, stirring occasionally, until chicken is cooked through and tender and liquid has thickened slightly, about 10 minutes.
Add eggplants, and continue to cook, adjusting heat as needed to maintain a simmer, until eggplants are just cooked through but still have some bite to them, about 3 minutes. Remove from heat, add sweet basil, and stir until wilted and incorporated.
Transfer curry to a large serving bowl or divide between individual bowls, and garnish with reserved thinly-sliced makrut lime leaves. Serve with cooked jasmine rice.
Thai apple eggplants, often labeled simply as “Thai eggplant,” can be found in Southeast Asian and Chinese markets, as well as online. While they differ greatly in flavor and texture, Japanese or globe eggplant can be substituted for this recipe (use an equal amount by weight); cut eggplants into 2-inch pieces and proceed with the recipe as written. Once cut open, the flesh of Thai apple eggplants will quickly oxidize, so once you’ve quartered them, it’s a good idea to place them in water until you’re ready to add them to the curry.
When purchasing coconut milk, look for versions like this one from Aroy-D that have "100% coconut milk" as the only listed ingredient, rather than those made with coconut extract and water.
Makrut lime leaves can be found at Southeast Asian and South Asian markets. If you’re lucky you will find them fresh, but it is more common to find them frozen (note that they are often sold under a different name that we avoid using, as it is a derogatory term in some contexts).
Palm sugar can be found in Thai markets, as well as some nationwide supermarket chains like HMart, and also online.
Make-ahead and Storage
The finished curry can be refrigerated in an airtight container for up to 3 days. Reheat gently on stovetop before serving. If you plan on making the curry a day in advance, hold off on adding the sweet basil leaves in Step 5; stir them in at the last minute when reheating the curry before serving.