In a deep pan, add the stock along with the lemon juice, galangal, lemongrass, fish sauce, sugar and lime leaves. Bring to a boil, reduce the heat and let it simmer for 15 mins.

Now, add red chilli paste and give it a nice stir. Then, add chicken, shallots, mushrooms, chillies and salt to taste. Let the soup simmer for another 15 mins.

Once the chicken is half cooked, add the tomatoes and shrimps.

When the shrimps become pink in colour and the chicken is completely cooked, take the soup off the heat.

Serve hot in separate soup bowls and garnish with coriander sprigs.

Note: If making with only vegetables, add sliced carrots, finely chopped french beans and thinly sliced babycorns when you put the stock to boil.