One story has it that the Italian Beef sandwich was started by Italian immigrants who worked for the old Union Stock Yards in Chicago. They often would bring home cuts of beef sold by the company. It was slow-roasted to make it more tender, then slow-simmered in a spicy broth for flavor. Both the roasting and the broth used Italian-style spices and herbs. The meat was then thinly sliced across the grain and stuffed into fresh Italian bread.

According to Scala's Original Beef and Sausage Company (formed in 1925), this meal was originally introduced at weddings and banquets where the meat was sliced thinly so there would be enough to feed all the guests. It rapidly grew in popularity and eventually became one of Chicago's most famous ethnic foods: the original Italian beef sandwich.