Local places usually have the best versions of this sandwich and it's worth the effort to scout them out if you're in one of the areas in the Midwest which are mentioned in the other comments - Missouri, Indiana, etc. You'll see them called Pork T, Big T, Texas T. But if you're somewhere and see a Culver's, they have a fairly passable version, for a chain. Nothing nearly as huge as the one pictured above. You may run across what's called a "chuckwagon", and those are usually the beef version of this sandwich. In any event, I think they're best with all the fixins - onion, lettuce, dill pickle chips, tomato, and insofar as a condiment - probably mayo.