I found the recipe for Süllöszelet magyarosan in a cookbook written by Mari Erdei. I have made several changes to the original recipe, e.g. I do not use as much butter as called for in the recipe or omit the flour to thicken the sauce. The sweet flavours of this fish is fantastic. The sauce here with tomatoes and bell peppers isn't overpowering the fish. Serve with a bread to dip up all of the sauce.