Grind Shrimp and Herring. Set aside. Puree tomatoes and onions. Pour oil into cooking pot and fry onion and tomato puree for 10 mins then add ground shrimp and herring. Cook until brown for 40 to 40 mins. Add salt to taste. Add ground chilli (Cayenne Pepper with the shrimp and herring if you want it to be spicy.