The best Philly cheese steak I've ever eaten was in Cambridge, MA, at Campus House of Pizza (IIRC) back in the mid-70's.
Well, OK, it wasn't exactly a Philly cheese steak - instead they called it a 'mushroom cheese steak'. It's exactly the same, even though it's entirely different.
(Yeah, I know that purists will laugh at me and call me names, but so what.)
You need to get really, really thin, shaved steak. You may have to go to a real butcher to get it, if the butcher in your local supermarket doesn't have it or make it.
Then you need to have a flat griddle like the ones that they make scrambled eggs on in a 40's era diner, and have it heated up super hot so that when you pour some oil onto it, it immediately sizzles. It helps if the griddle hasn't been thoroughly cleaned since the 1940's either. Then you have to dump a clump of the shaved steak onto the oil, and as it sizzles away, attack it with some kind of scary-looking metal cooking implement, preferably a meat cleaver that also does double duty making hash-browns in the off-season, and kinda cut up and fold over and smush around the steak, while adding a bunch of sliced mushrooms into the mix. Throw some salt on it while you're at it. And slice a long bun in half, and put the two halves sliced-side down onto the griddle nearby.
When it's done and almost ready to eat, you'll know it by the yummy smell. At the last possible moment, use the cleaver to gather the shredded steak-and-shroom combo into a pile and then put two slices of provolone cheese on top of it, then put the bun halves onto a paper plate, and use the cleaver to sweep up the hot melty goodness and dump it onto one half of the bun. Cover it with the other half, yell out the name of the customer and ask if they want a cold can of Coke with that (real Coke, not Diet Coke or Pepsi), and collect $1.90 as the delighted customer walks away with his prize.