The style is often traced to San Francisco's El Faro taqueria in the 1960s, where oversized flour tortillas were steamed soft specifically so they could hold double the usual fillings without tearing.
A steamed, oversized flour tortilla is packed with rice, beans, meat, salsa, sour cream, and cheese, rolled into a tight cylinder, and wrapped whole in foil to eat by hand. Taquerias throughout San Francisco's Mission District have served it this way since the 1960s.
Philly Cheesesteak