Why It Works
- A combination of fresh and dried chiles in the curry paste gives this curry layered heat with fruity notes.
- Unlike other curries that require cooking the paste in fat before adding more liquid, this curry is simply made by simmering the paste with water and seasonings, which allows for the paste to be easily made in a countertop blender as well as in a traditional mortar and pestle.
- Tamarind paste and lime juice give the curry its distinctive sour punch, which is balanced by the sweetness of palm sugar and bitterness of fresh turmeric.
Generally speaking, there are two styles of gaeng som, a spicy and sour water-based Thai curry that typically features seafood of some kind. One is from the southern part of Thailand and one is from the country's central plains; this recipe is for the Southern-style gaeng som, which is referred to as gaeng leung or gaeng som phak dtai outside of the south. While both versions share a spicy-sour flavor profile, use water or stock instead of coconut milk, and typically incorporate a combination of seafood and vegetables, they each use ingredients that are readily available in their respective regions.
In the South, the curry paste that forms the base of the curry is made from fruitier and much spicier chiles that come in a range of colors, like prik khee nuu suaan, prik deuuay gai, and prik gariiang, and consequently the curry has a lighter, brighter color. You'll commonly find saltwater fish like mackerel (pla thuu) or brackish water fish such as mullet (pla grabaawk) or barramundi (pla gapohng) added to the curry in the South, although you'll also sometimes see it made with shrimp or even pork. You'll find all kinds of vegetables and fruit added to the curry, too, including pineapple, pickled bamboo, elephant ear stalks, hearts of palm, and lotus stems, and lime juice, tamarind, or asam fruit are commonly used as souring agents.
The central plains version of the curry is a little sweeter, due to the inclusion of palm sugar in the curry paste, and slightly less spicy because it uses different chiles; it's also a relatively simple curry paste, and can consist of just spur chiles (prik cheefa), shallots, and shrimp paste, although sometimes grachai (also known as fingerroot or wild ginger) is added for its distinctly piney aroma (it's also considered a cooling spice that blunts any fishy odors), and sometimes the paste is pounded with a little boiled fish to give it a thicker texture. Fresh water fish such as snakehead fish is usually added to the curry along with vegetables like cabbage, Napa cabbage, long beans, okra, Thai morning glory (water spinach), and more.
For this recipe, I use a paste made from dried and fresh chiles, turmeric, shallots, garlic, and fermented shrimp paste, which I boil in water or stock and then season with fish sauce and tamarind, to add a subdued sourness. I then use this flavorful liquid to simmer pieces of green papaya and red snapper (pla gra), which take on a beautiful yellow hue from the turmeric. Right before serving, I add some freshly squeezed lime juice for a fresh and bright note of acidity.
I call for using chiles that are known in the US as “Thai chiles,” although I prefer to call this variety by its Thai name, prik jinda, since there are so many Thai chile varieties. The dried chiles produce a lingering heat at the back of the throat while the fresh chiles provide a sharp, front-of-the-mouth burn.
Prik jinda can easily be found in Southeast Asian markets. Fresh turmeric is increasingly available in stores like Whole Foods, but I find it best to go to South Asian markets. Trying to find fresh turmeric and prik jinda is important even if you choose to use store-bought curry paste, as this curry's flavor really relies on fresh ingredients. If you choose to use store-bought paste, make sure to look for one that is labeled gaeng leung, or sour yellow curry, and avoid using gaeng garee (karee, gari), known as yellow curry in English, which has a different flavor profile.
The curry paste can be pounded in a mortar and pestle or blended; if you choose to blend it, you'll need to add one cup of water to help break down the fibrous aromatics into a smooth paste. While blending will produce a more puréed paste with less textural nuance than a pounded paste, it's a completely acceptable quick method to make curry pastes for water-based curries. (A word of warning: The turmeric in the paste may stain your blender jar.)
This curry is best paired with side dishes that can counter its sour and spicy flavor profile, like galam plee pad nam pla (stir-fried cabbage with fish sauce and garlic) or a Thai omelette. And, as always, serve the curry and sides with jasmine rice.
- For the Curry Paste (see note):
- 1 teaspoon (4g) Diamond Crystal kosher salt
- 20 dried Thai chiles (8g), stemmed
- 15 fresh green or red Thai chiles (15g), stemmed
- One 4-inch (15g) piece fresh turmeric, thinly sliced
- 4 medium garlic cloves (20g)
- 2 small shallots (40g), quartered
- 1 tablespoon (30g) Thai shrimp paste
- For the Curry:
- 3 tablespoons (80g) tamarind paste
- 1 1/2 teaspoons (12g) palm sugar (see note)
- 3 tablespoons (45ml) fish sauce
- 6 1/2 ounces (about 2 cups; 185g) green papaya, peeled and cut into 2-inch by 1/2- inch-thick pieces, from 1 green papaya (see note)
- Two 6-ounce (170g) skin-on red snapper fillets, cut into 2-inch pieces
- 1 tablespoon (15ml) fresh lime juice from 1 lime
- Cooked jasmine rice, for serving
For the Curry Paste: If Using a Mortar and Pestle: Combine salt and dried chiles in a granite mortar and pestle and pound until chiles are broken down into small pieces, about 2 minutes. Pounding thoroughly between each addition to break down and incorporate ingredients into the paste (3 to 4 minutes of pounding per addition), add in the following order: fresh chiles; turmeric; garlic and shallots; shrimp paste. It should take about 15 minutes total to pound ingredients into a very fine paste with just a few visible pieces of fresh chile skin.
If Using a Blender: Combine salt, dried and fresh chiles, turmeric, garlic, shallots, and shrimp paste in a blender jar with 1 cup (240ml) water. Blend on high speed until smooth, 2 to 3 minutes.
For the Curry, If Using Pounded Paste: In a 3-quart saucepan, whisk together curry paste and 1 cup (240ml) water until well combined. Once thoroughly incorporated, add 3 cups (710ml) water, tamarind, palm sugar, and fish sauce, and stir to combine.
If Using Blended Paste: In a 3-quart saucepan, combine curry paste, 3 cups (710ml) water, tamarind, palm sugar, and fish sauce and stir to combine.
Bring to a boil over medium-high heat, add papaya and cook, stirring occasionally, until papaya is just beginning to soften but is still crunchy, 5 to 7 minutes. You may notice foam rising to the surface; this is normal, and should not be skimmed.
Add snapper and, using a spoon, gently submerge pieces in the curry. Continue to cook, gently stirring occasionally, until fish is opaque and just cooked through, 2 to 3 minutes. Remove from heat, and stir in lime juice.
Transfer curry to a large serving bowl or divide between individual bowls. Serve immediately with cooked jasmine rice.
Granite mortar and pestle, 3-quart saucepan
Palm sugar can be found in Thai markets, as well as some nationwide supermarket chains like HMart, and also online.
Green papaya is an unripe papaya that has pale white/green flesh. It is crisp and isn't sweet like a ripe orange papaya. Green papaya can be found in Southeast Asian markets.
Store-bought curry paste can be substituted for this recipe. Use one 4-ounce can of gaeng leung curry paste, which is often labeled as yellow sour curry paste.
Make-Ahead and Storage
The curry paste can be made in advance and refrigerated in an airtight container, with plastic wrap pressed directly against the surface of the paste to prevent it from drying out, for up to 1 week. The finished curry is best enjoyed immediately.