Wash fish well. if small fish are used, clean and scale them. If large steaks or fillets are used, cut them into serving pieces. Heat oil and fry the curry leaves until slightly brown, then add onion, garlic and ginger and fry until onion is soft and golden. Add all the ground spices and fry, stirring until they smell aromatic.
Add coconut milk and salt and bring to the boil, stirring. Simmer uncovered for 10 minutes, then put in the fish, ladle the liquid over it and simmer until fish is well cooked. Remove from heat and stir in lemon juice to taste.