Ingredients

• 500 g (1.1 lb) boneless, skinless chicken thighs, cut into 2.5 cm (1-inch) pieces
• 500 ml (2 cups) unsalted chicken stock
• 400 ml (one 13.5-fl-oz can) unsweetened full-fat coconut milk
• 1 lemongrass stalk, lower 12 cm (5 inches) bruised and cut into 5 cm pieces
• 40 g fresh or frozen galangal, sliced thinly (about 10–12 slices)
• 4 makrut lime leaves, torn to release aroma
• 150 g (5.3 oz) oyster mushrooms, torn into bite-size pieces
• 1–2 Thai bird's-eye chilies, lightly bruised (optional; adjust to taste)
• 2 tbsp (30 ml) fish sauce, divided, plus more to taste
• 1 tsp (4 g) palm sugar or white sugar
• 2 tbsp (30 ml) freshly squeezed lime juice, plus more to taste
• 2 tbsp chopped fresh cilantro, to finish
• Cooked jasmine rice, optional for serving (not included in soup cooking time)

Instructions

1. Wash and prepare the herbs and mushrooms. Bruise the thick lower part of the lemongrass, slice the galangal thinly, tear the lime leaves, and cut chicken on a separate board. Keep raw chicken away from ready-to-eat ingredients.
2. Bring the unsalted chicken stock to a gentle boil in a medium saucepan. Add the chicken pieces, reduce to a steady simmer, and cook about 12–15 minutes, stirring occasionally. Check the thickest piece with a food thermometer; it must reach 165°F (74°C).
3. Stir in the coconut milk, bruised lemongrass, galangal, torn makrut lime leaves and optional chilies. Keep the heat moderate so the coconut broth simmers gently rather than boiling vigorously.
4. Add the oyster mushrooms, 1 tbsp fish sauce and sugar. Simmer for 5–7 minutes, until the mushrooms are tender and the herbs have perfumed the broth.
5. Taste the broth. Add the remaining fish sauce a little at a time if it needs more savory saltiness; use less if your stock is seasoned.
6. Turn off the heat. Stir in 2 tbsp fresh lime juice, taste, and add a little more if needed. Adding lime at the end keeps its flavor fresh.
7. Remove the tough lemongrass, galangal slices and lime leaves before serving, or warn diners they are aromatic infusers rather than edible garnishes. Ladle into bowls, scatter with cilantro and serve hot, with jasmine rice if desired.

Tips and substitutions

• Galangal matters: The name tom kha refers to galangal. Ginger has a different flavor; if you substitute it, describe the result as a variation rather than traditional tom kha gai.
• Balance the broth: Fish sauce contributes salty umami; lime contributes sourness; sugar rounds out the flavor. Adjust in small amounts at the end.
• Choose the right mushrooms: Oyster or straw mushrooms are especially suitable. Button mushrooms also work, but their flavor and texture differ.
• Allergens: Fish sauce contains fish. Check packaged stock and sauces for other allergens. Coconut milk is part of the recipe.

Food safety and storage

Cook every chicken piece to 165°F (74°C) using a food thermometer. Wash hands, knife and board after contact with raw poultry; do not rinse raw chicken. Refrigerate leftovers within 2 hours (within 1 hour if above 90°F / 32°C) in shallow containers at 40°F (4°C) or colder. Use refrigerated leftovers within 3–4 days and reheat thoroughly to 165°F (74°C).

Serving ideas and related recipes

For a Thai-style meal, serve with jasmine rice and Thai basil stir-fry. Explore other aromatic soups such as Vietnamese bún bò Huế, or try Filipino chicken adobo for another chicken dinner.