In-N-Out's Protein Style burger replaces the buns with what?

In-N-Out’s Protein Style burger replaces the buns with lettuce.

Protein Style is a lettuce-wrapped version of an In-N-Out hamburger, cheeseburger, or Double-Double. The patty, cheese, tomato, onions, and spread remain essentially the same; the bun is removed and large lettuce leaves hold the ingredients together. The option is associated with the chain’s low-carbohydrate ordering choices.

It is often confused with the Flying Dutchman, another off-menu In-N-Out variation. A Flying Dutchman consists of meat and cheese without a bun, vegetables, or spread, while Protein Style still includes the burger’s usual toppings and uses lettuce as the wrap. Animal Style is different again: it changes the cooking and toppings, including mustard-cooked patties, grilled onions, pickles, and extra spread.

Protein Style began appearing in the 1970s and became one of In-N-Out’s best-known secret-menu options. Although the chain calls these variations part of its not-so-secret menu, customers generally need to request them rather than find them on the standard printed menu.