New York pizza lovers love nothing more than arguing about New York pizza, but all agree that the city’s characteristic version—baked in a coal-fired oven with a thin crust, high-quality canned tomatoes, and the best mozzarella—represents the pinnacle of American pizza. Gennaro Lombardi, the Neapolitan immigrant who painted the word “pizzeria” on his Spring Street window in 1905, is honored as the founding father of New York pizza. Not until 1933, however, when Patsy Lancieri opened Patsy’s in East Harlem, did New Yorkers meet the innovation that would change pizza from a sit-down meal to lunch on the run: Patsy’s sold its classic coal-oven pizza not only by the pie but also by the slice. By the 1950s, mass-market pizzerias were selling slices all over town, thanks to efficient new gas ovens that simplified baking and made individual slices of pizza easy to reheat. Along with the slice came another culinary innovation that changed the nature of pizza and made it a more popular lunch than ever: a choice of toppings.