For the Andalusian fish, dice the bacon and cook in a hot pan until translucent. Remove the bacon cubes from the pan and set aside. Fry the chopped onion in the fat. Add the chopped bell pepper salad, diced apple, mustard, ketchup and curry powder if desired, let it steam a bit and add bacon cubes again.
Clean, acidify and salt the fish fillet and place it in the shape of a roof tile in a greased ovenproof dish. Spread the sauce well over the Andalusian fish and steam in the oven for about 30 minutes. (Duration depends, of course, on whether fish is used fresh, or frozen).