1. Clean and wash the fish thoroughly with turmeric powder and salt water to clean them.
2. In a large bowl, add salt, 1/2 the portion of chilli powder, pepper powder, cumin powder, dhaniya powder, turmeric powder.
3. Rub the fish with this mix.
4. Marinate for a couple of hours in the freezer.
5. A couple of hours later, soak tamarind in 1/2 cup of water for 30 minutes and extract the juice.
6. In a kadai, heat oil, add mustard seeds and let it splutter. Then add cumin seeds, curry leaves, green chilli and saute.
7. Then add onion, shallots and saute until it turns golden brown. Between add some turmeric powder and salt.
8. Add tomato and let it become soft and mushy.
9. Add ginger garlic paste and let the raw smell disappear.
10. Then add tamarind water and bring to a boil then add the remaining portion of chilli powder, pepper powder, cumin powder, dhaniya powder, turmeric powder.
11. Add 1/2 a cup of water and boil. (Can add more water for a thinner gravy)
12. Then add marinated fish and let it blend well.
13. Add more salt and spice if required.
14. Let the fish cook on a low flame for 15-20 minutes.
15. Garnish with coriander/cilantro leaves and serve hot with rice or rotis.
16. Fish curry usually tastes better when consumed the next day of preparation.

Recipe courtesy: Food for 7 Stages of Life