Greese is part of it, but not wholly. The following is the best way to make a cheesesteak:
Requirements, in no particular order:
1. A pan big enough to fit the whole cheesesteak lengthwise.
2. Crisco.
3. Sliced Onions (optional).
4. A slab of beef (sliced lunch beef and ground beef are unacceptable, this must be a slab of compressed ground beef. If you try to use a steak of any kind I will castrate you).
5. Cheese.
6. A real bun, sourdough is good, but as long as it's soft it should be fine.
7. Lemon pepper (optional but it's awesome).
8. Metal spatula
Steps, in a very particular order:
0. Slap a big hunk of lard (Crisco is fine) on the pan. Let it cook down a little, then use your spatula to put the chunk back. Spread the lard around the pan, giving a nice coating. Scrape any excess into a corner somewhere.
1. Dump the beef on the pan. Doesn't matter how, really, as long as it all gets cooked.
2. Put the onions on about 45 seconds after the beef, but do not mix them in!!!! Put them aside, in their own little pile.
3. Let it all cook.
4. About 2 minutes before the beef is done, sprinkle some Lemon pepper over top of the beef.
5. About a minute before it's all done cooking, spread the beef out into a line, the length of the roll.
6. Lay a few slices of cheese (I prefer American, but Swiss works) right on top of the beef.
7. Take the roll and slice it LENGTHWISE down the middle, but not all the way through (kind of like a hotdog bun). You can do it on the top or side (side is better).
8. Open the roll, and put it right on top of the cheesey beef.
9. Slide the spatula under the beef, forcing it into the roll, and flip the whole thing over into your hand (not back onto the pan).
10. Take the onions and sprinkle them across the top of the beef.
11. Slice (...unlengthwise) all the way through the middle (perpendicular to the first cut), so that you now have 2 halves.
12. Add salt, pepper (just regular pepper), and ketchup. Anything else is heresy.
13. Eat.