Clean 500 grams of fresh fish under running water, removing scales, guts, and fins if needed, then cut it into medium-sized pieces of about 2–3 inches.
Marinate the fish with ½ teaspoon salt and ¼ teaspoon turmeric powder, rub gently, and set aside for 15–20 minutes to infuse flavor and reduce odor.
Soak a small lemon-sized ball of tamarind or 1 tablespoon tamarind paste in ½ cup warm water for 10–15 minutes, mash well, strain, and keep the tamarind water aside.
In a blender, grind 1 cup grated coconut, 4–5 dried red chilies, 1 tablespoon coriander seeds, 1 teaspoon cumin seeds, 4–5 garlic cloves, 1-inch ginger piece, 1 teaspoon turmeric powder, 1 tablespoon tamarind pulp, and 1 teaspoon red chili powder into a smooth paste using a little water.
Heat 2 tablespoons coconut oil in a pan on medium flame, add the ground masala paste, and sauté for 3–4 minutes until fragrant and cooked.
Pour in water to adjust curry consistency, stir, and let the masala base simmer gently.
Add 2–3 kokum rinds, ½ teaspoon Sichuan pepper, salt to taste, and the prepared tamarind water to the simmering curry, mix well, then gently place the marinated fish pieces inside.
Cover the pan and cook for 7–10 minutes until the fish is tender, then garnish with coriander leaves or green chili and serve hot with steamed rice or Goan poi bread.