When you make your own burgers you normally need to put some extras - pickled cucumber, relish, ketchup, mayo, mustard or other condiments - in the buns to make the burger more tasty and juicy. Alternatively you can make a burger sauce that already has most of these in it - then just spoon some onto the bottom half of the bun, add some lettuce, pop on a patty and your burger's ready to go! Any leftover sauce is useful for sandwiches and wraps.