Step 1

Bruise the lemongrass stems with the back of a knife and cut each one in half. Halve the mushrooms, or slice if large. Cut the chicken breast fillets in half lengthways, then thinly slice against the grain.

Step 2

In a saucepan, bring the chicken stock, lemongrass, ginger, chilli and caster sugar to a gentle simmer over medium-high heat. Add the chicken, mushrooms and coconut milk.

Step 3

Simmer (without boiling) for 5 minutes, stirring, until chicken is cooked. Add fish sauce and lime juice – the soup should taste hot, sour, lightly sweet and salty.

Step 4

Ladle the soup, chicken and mushrooms into warm bowls, then scatter with mint and basil leaves.