Tom Kha: Thai Coconut Soup with Lemongrass and Lime
Creamy, zingy and soothing
Tom kha gai is the gentler, creamier cousin of tom yum, a soothing Thai soup of coconut milk perfumed with lemongrass, galangal and lime. This one finishes with a drizzle of roasted chilli oil, which floats in glossy ruby pools and brings a smoky, mellow heat. The balance of creamy, sour and savoury is wonderfully restorative, equally good as a light supper or a cold-weather pick-me-up.
Tom Kha: Thai Coconut Soup with Lemongrass and Lime
Ingredients
- 2 stalks lemongrass, bruised and cut into lengths
- 5cm piece galangal (or ginger), sliced
- 6 kaffir lime leaves, torn
- 400ml chicken or vegetable stock
- 1 tin (400ml) coconut milk
- 300g boneless chicken thighs, sliced (or 250g mushrooms for a veggie version)
- 200g mushrooms, halved
- 2 tbsp fish sauce
- 1 tsp palm sugar (or brown sugar)
- 2-3 tbsp lime juice
- 2 tbsp roasted chilli oil (nam prik pao or chilli oil)
- Handful of fresh coriander
- 1 red chilli, sliced, to serve
Method
- Put the stock in a saucepan with the lemongrass, galangal and torn lime leaves. Bring to a simmer and infuse for 5 minutes so the aromatics perfume the broth.
- Pour in the coconut milk and return to a gentle simmer; avoid a hard boil, which can make it split.
- Add the sliced chicken and poach gently for 6-8 minutes until cooked through.
- Stir in the mushrooms and cook for a further 4-5 minutes until tender.
- Season with the fish sauce and palm sugar, stirring until the sugar dissolves.
- Take the pan off the heat before adding the lime juice, so its fresh sourness is not dulled.
- Taste and balance: it should be creamy, salty, sour and faintly sweet all at once.
- Fish out the woody lemongrass and galangal pieces if you prefer a tidier bowl.
- Ladle into bowls and drizzle a generous swirl of roasted chilli oil over each.
- Finish with fresh coriander and sliced red chilli, and serve hot.
3 The Story
Tom kha, most often made with chicken as tom kha gai, is one of the most comforting dishes in the Thai repertoire. The name is wonderfully literal: tom means to boil or simmer, kha is galangal, and gai is chicken, so it is simply boiled galangal soup with chicken. That galangal is the key to its identity. Though it looks like ginger and is sometimes substituted with it, galangal has a sharper, more piney and citrusy bite that gives the soup its distinctive fragrance.
Where the fiery tom yum relies on a clear, sour-and-spicy broth, tom kha softens everything with coconut milk. The coconut tames the heat and acidity into something rounded and creamy, which is why this soup is often the gateway dish for people new to Thai flavours. It is rich without being heavy, and deeply aromatic thanks to the trio of lemongrass, galangal and makrut lime leaves that infuse the broth. These aromatics are meant to flavour rather than be eaten, so it is normal to leave the woody pieces on the side of the bowl.
Balance is everything in Thai cooking, and this soup is a clear lesson in it. Salty fish sauce, sour lime, a little sweetness from palm sugar and the creaminess of coconut all have to find equilibrium. Adding the lime juice off the heat keeps it bright and fresh, since prolonged heat dulls its sharpness. Taste as you go and adjust; the exact amounts will depend on your fish sauce, your limes and your own palate.
The roasted chilli oil finish is a natural flourish rather than a stretch. Nam prik pao, a Thai roasted chilli paste made with dried chillies, shallots, garlic and a little sugar, is a classic enrichment for tom yum and lends a smoky sweetness and gentle warmth. Swirled over tom kha just before serving, a roasted chilli oil floats in pretty pools on the coconut surface and adds depth without overwhelming the soup’s soothing character. A plain good-quality chilli oil works well too if that is what you have. Serve it on its own as a starter, or with steamed jasmine rice alongside to make a fuller meal.
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