Fish Curry (Kodavas-Style)

1. Cut each mackerel into 2 pieces and make a few cuts on the surface of the fish, so the marinade can permeate the inside of the fillets. Place fish into a bowl and add 1 1/2 tablespoons ground turmeric, 1 tablespoon tamarind paste, 2 teaspoons salt, and 2 to 3 cups water. Stir to dissolve salt and soak fish in the marinade, about 10 minutes.

2. Discard liquid and rinse fish twice under cold running water. Return fish to a bowl and add chili powder, remaining 1 1/2 tablespoons ground turmeric, 1 tablespoon tamarind paste, and salt to taste. Mix well and set aside.

3. Combine cumin seeds, coriander seeds, black peppercorns, and mustard seeds in a dry skillet and toast over medium-low heat until fragrant, 1 to 2 minutes, shaking skillet repeatedly so spices don't burn.

4. Remove coconut meat from coconut and chop. Combine toasted spices, coconut, garlic, and ginger in a mortar and pestle and grind into a paste, adding a little water as necessary to get the consistency of the masala right. Mix in onions and green chili.

5. Heat oil in a heavy pot. Add masala paste and 1 1/2 cups water. Bring to a boil over medium-high heat. Add marinated fish and check water level. You might need to add more water. Simmer until fish flakes easily with a fork and sauce has thickened, about 15 minutes. Season with salt to taste.

Cook's Notes:

You can use a variety of fish instead of mackerel, e.g. sardines, pomfret, or even shrimp.

Instead of tamarind paste, the original recipe asks for kachampuli (black vinegar) which can be hard to find.