Mix the fish pieces with 2 tablespoon fish sauce, set aside.
Heat oil in a pot. Fry the ginger, chilli pepper and garlic. Pour in the chicken stock and coconut milk, heat up. Be careful not to boil over! Add the fish sauce, lime juice and sugar. Let simmer for 5 minutes. Now add the tomatoes and the fish, simmer for another 5 minutes, season to taste, done!
This recipe is enough for 4 people as a starter or for 2 as a main course.