1. Sprinkle some salt on the fish and keep aside.
2. Heat the oil in a pan; add onion and saute for 3 minutes till soft. Add garlic and ginger; saute for 30 seconds.
3. Add recheio spice paste and stir-fry for 2 minutes, adding a little water if necessary.
4. Add 1 1/4 cups water and bring the mixture to the boil, lower heat, cover and simmer for 10 minutes.
5. Add the fish, salt to taste, and sugar. Simmer for 5 minutes until the fish is cooked and the gravy is thick. Adjust seasoning. Add vinegar, if necessary. Remove from heat.
6. Serve hot with rice or bread