Beef is the benchmark burger protein, but there are many other possibilities, ranging from poultry (including chicken and turkey) to specialties such as pork, bison, salmon, lamb, and other kinds of seafood. Many operators will offer more than one type of patty, either as part of a mix-and-match build-your-own burger program, or in the form of curated signature burgers with their own carriers, toppings, and condiments.