For an extra layer of flavor, consider adding a drizzle of high-quality honey or a smear of Dijon mustard to the burger. Feel free to experiment with different types of doughnuts, such as chocolate or maple-glazed, to create your own signature Luther Burger. If you're feeling adventurous, a sprinkle of smoked paprika on the beef patties adds a delightful smoky depth. To prevent the doughnuts from becoming soggy, assemble the burgers just before serving.