The Shanti Inn in Gunder, Iowa, actually has a Postville, Iowa, address (see map). But it's one of those out of the way places that you need to go to just to experience a Gunder Burger.
Actually, a Gunder Burger is too big to eat for most people. Two people can even have problems with it. I've had burgers that were bigger - those were more novelties than anything. The Gunder Burger is big and it's good. A local bakery makes the buns for the burgers and they're light and fresh - a perfect compliment for the burger.
And The Shanti Inn is the only place I've ever eaten at that features Country Bob's All Purpose Steak Sauce on the tables. That's about my most favorite steak sauce on the market today.
Cindy and I stopped in there one time during a drive through beautiful NE Iowa. Cindy has family up there and we tried to go on a Sunday after we saw her grandmother in Volga, IA, but it turned out the place was closed. So we drove up on a Saturday. We were the only ones in the place and got to talking to the lady who was cook, bartender and waitress. We noticed she had a Shanti Inn coozie and I said, "I'll buy one of those."
She said, "Well, I don't have one to sell. Some advertising guy came by and gave this to the owner to show him how one would look. He never ordered any."
I was kind of crestfallen about that, and she finally said, "Well, hell, here. Just promise me you won't tell anyone where you got it."
That was about 8 years ago - I think the statute of limitations on keeping promises runs out after seven years...
The place is worth the drive, even just for the scenery in and around Gunder.