Get your whole fish cut into your desired size piece, make some cuts for easier marination.marinate with salt and vinegar/lemon and let it sit for at least 20 mints, then deep fry. (You can buy the one that are. deep fried already)

Once you are done, fry your onion till soft and your ginger and garlic stir until you can smell the aroma,add your tomato sauce puree and cook for 3mnts,add salt,your fish pieces and cook covered. for about 5mints turn gently so that both sides gets the gravy, reduce the heat,add the capsicums stir gently.