Fry in 2 or 3 tablespoons of either mustard oil, gingelly oil, olive oil, or any other fat, 2 small onions, and 2 to 3 cloves of garlic, sliced finely; then add the curry mixture and cook for another 5 minutes.
Add sufficient coconut milk to make a semi-thick gravy.
Add salt to taste.
Add fish to the sauce, keep the pan uncovered, and simmer gently until the fish is cooked.
Shake the pan occasionally to prevent the fish from sticking to the pan.