Serious Eats - seriouseats.com

To me, a hamburger needs to have two qualities to be justified as one: being made from hamburger, and having something to turn into a sandwich. If that's a bun, or toast, or lettuce doesn't matter to me.

You can't really split hairs on the patty melt if you accept toast but not sourdough. It's an accepted bread item holding a hamburger.

Jack In The Box had a patty melt a few years ago, but I never had the courage to try it as I actually do love patty melts, and I think I'll stay away from Carl's Jr.'s attempt as well.

You can't be serious. A burger is a burger regardless of your means of conveyance. Frankly, I think that buns are overrated. They are nice and all, but I actually prefer using a couple of pieces of toast instead of a bun; it's less bread to get in the way of the meat. Don't get this statement misconstrued, I won't turn down a bun, but I'll choose a couple slices of toast if I have the option.

Saw an earlier post about tortilla burgers and had to agree they can be tasty, but they aren't really burgers. But as for patty melts, the swiss/grilled onion combo is what makes this burger special, and I can see why toast is traditional for them. I'd guess any diner would sub a bun for the toast, if that keeps it "pure" for you. But you might regret the choice if the bun turns soggy. Plus, you can request wheat toast in any hole-in-the-wall, but rarely can you find a wheat bun, even in hoity-toity places.

I realize I may be going out on a limb on this one, but I've enjoyed a "cheeseburger club" sandwich at a diner near Rockefeller Center. Three slices of toast, melted cheese, typical burger patty, bacon, lettuce and tomato. Somehow, the toast brings something to the party that the usual diner bun doesn't.

I wouldn't eat ALL or even MOST of my burgers this way, but it's a nice change of pace and definitely still a burger in my book.