I was born and raised in Philadelphia and this was my favorite lunch at the luncheonettes (sandwich shops). Places throughout the rest of the Country that claim to make Philly Cheese Steaks just do not get them to taste the same, and one of the reasons is that they do not use extra-virgin olive oil. Anyone who says that Pat's and Gino's in South Philly uses Cheez Wiz, is talking about the way they make it now. The old authentic way uses Provolone Cheese. Also, using deli roast beef is the same as using top round sliced wafer thin or frozen Rib-Eye roast shaved on an electric slicer. I was born in 1942 and this is the way they were made way back then. We are talking about authentic, not the way they are made now. If you make any changes with the ingredients or the directions, it will not be the same. Make it EXACTLY as written here.