Tom Kha Gai Broth

Combine the coconut milk and chicken stock in a medium saucepan. Add the galangal slices, lemongrass batons, and torn kaffir lime leaves. Set over medium heat and bring to a gentle simmer — not a boil. A full boil breaks the coconut milk emulsion and makes the broth grainy and oily. Let it steep at a lazy simmer for 10–12 minutes, pressing the aromatics against the side of the pan occasionally with a wooden spoon to encourage them to release their volatile oils. The galangal should start to look slightly translucent at the edges.

Add the sliced chicken thigh meat, mushrooms, and bruised bird's eye chilies to the simmering broth. Stir gently to separate the chicken slices. Maintain a gentle simmer and cook for 6–8 minutes until the chicken is just cooked through — it should feel firm when pressed with a spoon but not dry or stringy. The mushrooms will turn silky. Do not overcook the chicken or it will become rubbery; coconut broth continues to carry heat even off the flame.

Remove the pot from the heat before adding the fish sauce and lime juice — lime acidity is volatile and the bright topnote evaporates when cooked. Stir in the fish sauce first, taste, and adjust. Then add the lime juice in stages, tasting after each addition. The balance of this broth is everything: it must be simultaneously salty, sour, and lightly sweet from the coconut, with a background warmth from the chilies. If it tastes flat, add more fish sauce; if it tastes thin and sour, a pinch of palm sugar rounds it out.

Ladle the broth into serving bowls, distributing the chicken and mushrooms evenly. Scatter fresh coriander leaves over each bowl just before serving — do not stir them in. Do not serve the galangal, lemongrass, or kaffir lime leaves as food; they are eaten around. Provide a small dish of extra lime wedges and fish sauce at the table so guests can adjust to their own taste. The broth is meant to be sipped, not just spooned.