Clean de-boned fish, marinate with half of ginger garlic paste, some of the chilli powder, salt, turmeric and 1/4 cup tamarind pulp. Set aside for some time.

In a pan, heat oil, add whole garam masala and finely chopped onion. Fry until golden brown, add ginger garlic paste, remaining chilli powder and stir for a minute.

Add fish, and all the remaining ingredients. (Check the sourness of tamarind pulp and add according to taste. Add water to adjust consistency. Let it boil and simmer for 10 minutes. Serve with hot rice or roti.