Pour the chicken stock and coconut milk into a large saucepan set over a medium heat. Tip in the galangal, lemongrass and lime leaves, and bring to a gentle simmer, around 6-8 mins. Keeping at a gentle simmer, add the chicken. Cook for 8-10 mins until tender and cooked through.

Stir in the mushrooms and chillies, and simmer for a further 3-5 mins until everything is cooked through. Sprinkle in the sugar and 3 tbsp each of the fish sauce and lime juice. Taste and add the remaining if required.

Remove the galangal, lemongrass and lime leaves before serving using a slotted spoon. Ladle into bowls and serve with coriander leaves sprinkled over and steamed rice on the side. Will keep chilled for up to three days. Leave to cool first.