Name: Tom kha gai (Thai chicken and coconut soup)
Prep time: 15 min
Cook time: 20 min
Total time: 35 min
Cuisine: Thai
Ingredients: 500 ml chicken stock, unsalted or low-salt (check the label if you need it gluten-free); 40 g galangal (about an 8 cm piece), thinly sliced; 3 lemongrass stalks; 6 makrut lime leaves; 400 ml full-fat coconut milk; 400 g boneless, skinless chicken thighs; 150 g oyster mushrooms, torn into pieces, or straw mushrooms, halved; 3 tbsp fish sauce (check the label if you need it gluten-free), plus more to taste; 2 tsp palm sugar (or light brown sugar); 3 tbsp lime juice (from about 2 limes), plus more to taste; 3–6 bird's eye chillies, lightly crushed; 1 small bunch coriander (cilantro), roughly chopped; Steamed jasmine rice, to serve

Tom kha gai (Thai chicken and coconut soup)

Chicken poached in coconut milk and stock perfumed with galangal, lemongrass and lime leaf, finished with fish sauce and lime. Sour, gently sweet and rich without being heavy.

By the Soupmap Culinary Team

Prep: 15 min
Cook: 20 min
Total: 35 min
Effort: Easy
Serves: 4

Broth richness 6/10

Spice 4/10

Comfort 6/10

Ratings by the Soupmap Culinary Team, not readers.

Method

Prepare

Trim the lemongrass to the bottom 12 cm or so and peel off the tough outer layer. Bash the stalks along their length with the back of a heavy knife and cut them into 4 cm lengths.
Tear the lime leaves into pieces, pulling out the tough central rib. Slice the chicken across the grain into thin, bite-sized pieces about 5 mm thick, so it cooks quickly and evenly.

Cook

Bring the stock to a boil in a saucepan over high heat. Add the galangal, lemongrass and lime leaves, lower the heat to medium and simmer until very fragrant, 5 minutes.
Shake the can, then stir in the coconut milk and bring it back to a gentle simmer over medium heat, with small bubbles around the edge rather than a rolling boil.
Add the chicken, stirring to separate the pieces, and poach at a gentle simmer until cooked through with no pink in the middle, 6–8 minutes. Add the mushrooms for the last 3 minutes.

Season and serve

Turn off the heat. Stir in the palm sugar, the chillies, about two-thirds of the fish sauce and most of the lime juice.
Taste: it should be sour and salty first, then creamy and faintly sweet. Add more fish sauce or lime juice until it's right.
Scatter with coriander and serve straight away with rice. Leave the galangal, lemongrass and lime leaves in the bowl, but don't eat them.

Swaps

Cooking for coeliac disease or an allergy? Check every label: the notes below say which ones matter.

Gluten-free

Already gluten-free as written, as long as the fish sauce and chicken stock are labelled gluten-free (some fish sauces contain wheat).
In the variations, light soy sauce contains wheat, so use tamari labelled gluten-free, and check the label on nam prik pao.

Plant-based

Make tom kha het (see Variations): vegetable stock, 400 g mixed mushrooms and 200 g cubed firm tofu, seasoned with salt or tamari labelled gluten-free instead of fish sauce. Leave out the nam prik pao, which usually contains dried shrimp; everything else is already vegan.
Without fish sauce it's less deeply savoury, so season boldly and lean a little harder on the lime. It's a recognised version in its own right, not a compromise.

High-protein

More chicken: use 600 g thighs instead of 400 g: about 9 g more protein per bowl. They still cook in 6–8 minutes if sliced thinly.
Prawns too: add 200 g peeled raw prawns with the mushrooms and cook until pink and opaque all the way through, 2–3 minutes: about 9 g more per bowl.
Tofu: add 200 g cubed firm tofu with the mushrooms: about 7 g more per bowl.

Tips

Be generous with galangal. It's the soup's name and its main flavour. Young galangal doesn't need peeling; frozen galangal is a good substitute for fresh. Ginger is warmer and sweeter and makes a nice soup, but not tom kha.

Simmer, don't boil. Once the coconut milk is in, keep the heat at small bubbles around the edge. Hard boiling breaks the emulsion, and the fat separates into an oily, slightly grainy layer.

Choose thighs. Thigh meat stays tender in the hot broth; breast dries out quickly. If you use breast, slice it thinly and check it after 5 minutes.

Use full-fat coconut milk. Light coconut milk gives a thin, watery soup. Shake the can before opening so the cream and liquid are evenly mixed.

Season off the heat. The lime stays fresh and floral, and you can taste the balance properly as you go.

Make ahead and storage

The aromatic stock (step 3) can be made up to 2 days ahead and kept in the fridge; finish the soup when you're ready to eat.

Refrigerate leftovers within 2 hours and eat within 3 days. Reheat gently until steaming hot all the way through, without letting it boil hard, and freshen with a squeeze of lime.

Freezing tends to make the coconut milk grainy, so I wouldn't.

Variations

Prawns (tom kha goong): use 400 g peeled raw prawns instead of chicken and cook them until pink and opaque all the way through, 2 minutes.

Mushroom (tom kha het): use vegetable stock, 400 g mixed mushrooms and some cubed firm tofu, and season with salt or light soy sauce instead of fish sauce. Light soy sauce contains wheat, so use tamari labelled gluten-free if you need it.

A touch of red: stir 1 tbsp nam prik pao (Thai roasted chilli paste, smoky and sweet) into the soup with the seasoning for colour and depth. Check the label if you need it gluten-free.