When we visited Chicago over the summer, we brought back all sort of food, including some Italian beef for sandwiches. I also stocked up on some peppers that are hard to find here, including the "authentic" hot giardiniera peppers for the sandwiches.
So here it is, on home made bread (of course):
It's pretty simple, just the beef, plenty of juice, hot giardiniera, and sweet bell peppers. That's it.