1. Rinse the fish in cold water, drain and rub with salt, pepper and lemon juice. Set aside for 1 hour.
2. In a heavy saucepan fry the garlic in hot oil to extract the flavor, then discard the garlic. Cook onions in the same oiluntil transparent. Add tomatoes, olives, capers and chilies to the onions. Mix together and add the fish. Simmer over low heat until the sauce is thick and the fish is cooked, 10-15 minutes.