Rinse the fish cutlets and trim away the fins with a pair of scissors. Still using the scissors, snip out the centre bone from each cutlet to leave a space for the stuffing. Place the cutlets in a well-buttered baking dish and set aside while preparing the stuffing.
Combine the breadcrumbs, suet and parsley in a small basin. Add a seasoning of salt and pepper. Lightly beat the egg and then mix about
Brush the remaining egg over the fish and sprinkle with a few toasted breadcrumbs.
Cover with a buttered paper or foil and bake in a moderate oven (180°C., 350°F., Gas Mark 4) for 20–25 minutes. Garnish with wedges of lemon and serve.