Mix the turkey, crumbs, onions, parsley, salt, garlic powder, pepper, Worcestershire sauce, and mustard in a bowl. Shape the mixture into ½-inch thick patties, and place it on baking sheets. Bake at 325 ºF for 15-20 minutes. Place a slice of mozzarella cheese on top of each patty and let it melt. Place the melted patties in the sandwich bun slit, garnish with slice of green pepper and tomato, and serve.