Cut the chicken breast into thin strips, halve the mushrooms and finely grate the ginger.
Heat the coconut milk with water and the ginger in a saucepan until the liquid is hot but not boiling hard.
Add the chicken to the hot coconut broth and let it poach gently until cooked through and tender.
Add the mushrooms and cook briefly so they soften but keep a little bite.
Take the pan off the heat, stir in the lime juice and season the soup to taste with salt.
Serve the tom kha gai soup straight away while it's hot and the fresh lime still comes through clearly.
Good to know
This soup is simple, fragrant and pleasantly creamy. It's delicate without being thin. Just right when you want something warm with bright flavours.
Swaps
Chicken breast → turkey breast (similar protein content) | mushrooms → shiitake (also provide fibre, with a stronger aroma) | ginger → galangal (classic in tom kha, with a similarly fresh heat) | lime → lemon (also provides acidity and vitamin C)
Allergens
The recipe is naturally free from milk, egg and gluten, provided you don't use contaminated products. For children, keep the acidity and heat mild; in pregnancy, always cook the chicken right through.