I was just in Chicago a couple months ago. Got an Italian beef from Mr. Beef. I will say, a lot of the Chicago food staples are overrated. But this was genuinely one of the best "street food" sandwich shop Italian beefs I've had. A greasy treasure. They didn't skimp on the beef, it actually had flavor, the roll was crusty on top while a sopping mess on the bottom after 30 seconds, just pure perfection. If anyone is ever in the area I can't recommend visiting them enough. Get a sammich, they do live up to the hype.