Sooner or later, you're going to try one of these, as they spread all over the civilized world. The Bosna was invented in 1950 by the Balkan Grill Walter, a pretentious name for a tiny closet with a window in an alley off the Salzburger Altstadt. If you can bear the long lines of (mostly Austrian) enthusiasts, even in subzero weather, you'll be munching on the walk-around sandwich of your dreams.
Two skinny brats with onions, fresh parsley, a dusting of curry powder, and enough mild Austrian mustard to fill the toasted bun. Ketchup for the occasional American, although we don't recommend it. Sounds easy? Then why hasn't McDonalds pilfered the formula?