Clean the fish make close slits on both sides and set aside.
In medium sized skillet, fry together chilly powder, grated coconut, black pepper, turmeric powder and coriander powder. No need to add oil or water while frying these ingredients. Stir continuously on a medium heat until the masala gets a light brown colour. Let the masala cool for a little while. Blend the masala with green chillies, ginger and garlic along with a little bit of water (about 1 tbsp) and vinegar. Blend well to get a fine paste and set aside. Add salt to taste.
Apply the coconut masala on both sides of all the fish pieces. Wrap each masala covered fish separately in a banana leaf. Heat some oil in a pan and place the fish along with the banana leaf. Fry both sides well.
Garnish with lemon slices, cucumber and curry leaves if you like. Serve with Cucumber- Onion Rita.