I have very limited knowledge of Philly Cheese Steak sandwiches, as I don't remember ever getting one in a restaurant or deli. But we do occasionally fix sliced roast beef on sub rolls at home using Velveeta along with horseradish sauce and Grey Poupon mustard. Melted Velveeta (in the microwave) seems fine to me. Sounds like they might be somewhat like the Earl of Sandwich chain's roast beef (the Original) sandwich. Those are pretty good with Cheddar, but I think they have other cheeses available.
We tried a new restaurant (actually a sports bar) in town last week that supposedly serves original Buffalo hot wings and roast beef on kummelweck, another sandwich, but indigenous to the Buffalo and western NY area. Kummelweck is basically a large round roll, fairly firm, that contains caraway seeds and has salt crystals baked on the top. The sandwich is usually served with about the hottest horseradish sauce available. But no cheese. My wife is a Buffalo native and is an expert on the subject of "Beef on 'Weck," and I've had many of them myself, but not nearly as many as she has. Anyway, the local attempt at duplicating the real thing wasn't too successful (especially the rolls - too soft, and the beef was sliced too thick and undercooked, almost rare). The sandwiches were also far too expensive ($12). My wife gave them some advice about how they should be made (she's good at giving advice), but they weren't very interested in her opinion. Maybe things have changed in Buffalo.
