It was the 1930s in South Philly, and Pat Olivieri ran a hot dog cart near the Italian Market. One afternoon, Olivieri couldn’t stomach the thought of another hot dog for lunch, so he sent his brother to the butcher.

They chopped up and seasoned the fresh beef, topped it with onions and laid it across a bun. In that moment, a cab driver, also craving a change, opted for the brand-new concoction and convinced Olivieri he was on to something.