For the sauce, peel and finely dice the onions. Heat 10 g fat in a pot and fry the onions. Deglaze with the wine. Stir cornflour in the milk until smooth and add while stirring. Season to taste with lemon juice, paprika, salt and pepper.
Wash, chop and add the parsley. Peel, wash and thinly slice the potatoes. Fry them in the remaining fat until golden brown. Grease an ovenproof dish. Wash fish, dab dry and season with lemon juice, salt and pepper. Place on the bottom of the dish. Place slices of ham and cheese on top and pour the sauce over them. Clean, wash and cut the peppers into strips. Spread the paprika and potato slices on the sauce.
Place on the bottom of the dish. Place slices of ham and cheese on top and pour the sauce over them. Clean, wash and cut the peppers into strips. Spread the paprika and potato slices on the sauce. Bake in the preheated oven (electric cooker 200 ° C/ gas: level 3) for about 25 minutes. Serve garnished with olives, lemon slices and parsley