Filipino Hot and Sour Fish Soup

In a medium pot, combine the tilapia, pak choi, tomatoes and daikon radish. Stir together the tamarind paste and water; pour into the pot. Toss in the chilli peppers if using. Bring to the boil and cook for 5 minutes or just until the fish is cooked through. Even frozen fish will cook in less than 10 minutes. Do not over cook, otherwise the fish will fall apart. Ladle into bowls to serve.