A southwest Philly is a sandwich sometimes served at dinners in the southwestern United States that gains influences from the Philly cheese steak.
It is often prepared with a tri-tip or skirt steak as the meat of choice. This is not to be confused with a tri-tip sandwich though.
What makes a southwest Philly is the ingredients and marinade of the meat.
The meat is often soaked in a brine, with lime, garlic, and jalapeño. It is grilled, then sliced thinly across the grain, and placed on the bread (garlic bread or Texas toast). On top of the meat goes grilled onions and bell peppers, then pepper jack cheese is then melted on top. I find it best with liberally seasoned fries.
It is savory (butter on bread), sweet (grilled vegetables), and spicy (marinade), all the while being wrapped in tin foil to be carried around or eaten on the spot!