Clean and cut the fish pieces. In deep saucepan/kadhai or kalchatti, add fish, sliced onions or shallots, slitted green chillies, ginger, curry leaves, turmeric powder, chilli powder, salt, tamarind pulp and water. Bring to a boil and cover with a lid. Cook at medium flame. Add sliced tomato and cook for another 4-5 minutes. Cook until the fish gets done and adjust the gravy according to your consistency.
Add some curry leaves or coriander leaves and switch off. Add a tsp of coconut oil.