In a big pot, add water and bring to a boil.

Add tomatoes and onion and continue to boil.

Add prawns and cook for 2 minutes then remove the prawns and set aside to cool. Once cool enough, peel prawns leaving the heads and tail intact. Set aside still.

Back to the pot, add radish and string beans. Bring pot to simmer until vegetables are cooked.

Add mackerel and cook for another minute. Add kangkong.

Season with fish sauce & salt.

Add tamarind extract and green finger chilies.

Then bring back the prawns to the pot. Cook for another minute and the soup is ready to serve!

To serve, arrange the mackerel, prawns and vegetable in a small bowl then pour the soup. You can serve the soup with fish sauce and a piece of halved calamansi on the side.