The Employee Menu Hack At Katz's Deli You Need To Try

Katz's Deli is a New York City icon that has been around since 1888, where locals and tourists still flock for classic Jewish deli food. One of the things it's best known for is its towering sandwiches, like the $30.95 two-meat Combo Sandwich, which is the most expensive, and one of America's best Reubens. Its pastrami on seedless rye is also popular, but counter workers often pivot to a favorite off-menu hack: swapping the rye for a knish (via Instagram). Since this thick, dough-encased square of mashed potatoes is roughly the size of a bread slice, it makes for a perfect vessel.

Workers cut the knish, pronounced with a hard "k," in half horizontally, then pile the freshly sliced meat on one exposed potato side, which absorbs some of the juices. Mustard, the traditional knish partner, is slathered on the other side for the topper. Although customers cannot order this makeshift sandwich directly, they can simply request a pastrami sandwich with extra mustard and a side knish to assemble the creation themselves.

The sandwich isn't Katz's employees' invention, however. Other places actually have it on the menu, with variations like serving it with Russian dressing instead of mustard, grilling the potato side of the halves, or using another meat like corned beef, which is similar to pastrami. In fact, UBS Arena — the home of the NHL's New York Islanders — serves its Knishwich with pastrami, Swiss cheese, coleslaw, and mustard.

Knishes were brought to New York City by Jewish immigrants from Eastern Europe around the turn of the 20th century. The square versions, like those used in these sandwiches, are deep-fried and also known as Coney Island knishes. A company called Gabila's created the commercial standard for them in 1921, when Elia Gabay sold the ones his wife, Bella, made in their Manhattan apartment using her own recipe from a pushcart. They went on to become a favorite New York street cart and deli snack, and they are the most popular type at Katz's.

The more traditional knish is round and baked, and it can come with fillings other than potato. Common ones include spinach, broccoli, kasha (buckwheat groats), mushrooms, onions, and cheese. Additionally, you can find chef-y versions today with more gourmet fillings. Also unlike the square version, the round ones often have a circular opening in the dough on top that lets the filling show through.

Although knishes aren't that common beyond New York, Gabila's sells its square knishes frozen in supermarkets like ShopRite and Publix, and at warehouse retailers. You could make your own sandwiches with them using some of the meats and toppings mentioned above, or others that would go well with the potato base, such as roast beef, ham, cheddar, roasted peppers, or gravy. Breakfast sandwiches are a great idea, too, using standard fillings like eggs, cheese, bacon, and sausage, and maybe ketchup or a sprinkle of hot sauce.