Cut the fish into slices 1.5 cm thick. Salt them and let it stand for about 30 minutes in half vinegar. Drain them then roll them in flour and fry them in a highly heated sunflower oil. To the rest of the frying fat, add 1 finely chopped parsley, 1/2 tsp black pepper and remaining vinegar. Stir the sauce and leave it just to a boil, then remove from heat to cool. Arrange the fried fish dish and then pour the sauce.