In a bowl, mix the egg whites and whole egg. Add the mayonnaise and mustard.
Pour the bread crumbs in a separate bowl. Season the steak with salt and pepper. Dip the steak in the crumbs, covering both sides. Dip the steak in the egg. Then dip in the crumbs again.
Heat 50ml of the oil in a frying pan. Fry the steak on a high heat for four minutes each side until golden brown. Repeat with all the steaks. Add oil if needed.