The In-N-Out secret menu consists of special orders for burgers, fries, vegetables and shakes. For example, a protein-style burger is a burger with no bun wrapped in lettuce for a low-carb meal.
Any burger can be mustard grilled, which means that after cooking the first side, the cook adds mustard onto the patty before flipping it so that it can be cooked into the meat. Up to four burger patties can also be added to any burger order. One of the more popular secret menu burgers is the Flying Dutchman, which has two patties, two slices of cheese, no bun and only the condiments that are specifically requested.
The secret menu has multiple vegetable options, including adding chopped green chilies or customizing onions as either fresh or grilled and whole or chopped. A vegetable burger has all of the fresh vegetables offered on the menu without cheese or meat. Customers can vary how much salt is on any part of an order or how much a burger bun is toasted.
The secret menu also has customizable fries and drinks. Fries can be cooked a little less than normal, be made extra crispy or have cheese slices melted on top. Beverages like the root beer float and a Neapolitan shake are available on request as well.