Not diced tomatoes - you get a tomato wedge

Personally, this is my choice:
http://jimsoriginal.com/jimsoriginal/Welcome/

In Berwyn:
bigguyssausage.com
is great as well


There is a Jim's by the UIC campus off Roosevelt.

You can't go wrong at

goldcoastdogs.com

Stay away from Hot Doug's - VERY hipster and not worth the hype. They have all kinds of weird stuff like ostrich sausage, etc...