The runza is a sandwich that bakes its own wrapper shut. A soft, slightly sweet yeast dough is rolled thin, loaded with a seasoned mix of ground beef, shredded cabbage, and onion, then folded into a rectangular pocket and sealed completely before it goes in the oven. There is no second slice and no open face: the bread is built around the filling, and the closed seam is the entire reason the thing exists. It holds heat, holds shape, and holds a wet savory load without leaking, which is what separates it from a sandwich you have to eat over a plate.
As a sandwich it works because the dough and the filling are tuned to each other. The yeast dough is enriched enough to stay tender after baking but strong enough in the gluten to take the steam coming off cooked cabbage without splitting at the crimp. The beef is browned and the cabbage and onion are cooked down before they ever go inside, because the bake time is set by the crust reaching gold, not by the center coming up to temperature. Cabbage is the structural choice in the filling, not a garnish: it holds moisture and gives the beef a soft bulk that fills the pocket evenly so every bite is the same. The result is a self-contained hot meal sized to one hand, sturdy enough to carry through a cold afternoon in Nebraska without a wrapper or a fork. The Nebraska chain that built its identity on the format keeps the rectangular shape precisely because the flat seam sits flat and travels well.
The runza belongs to the German-Russian pocket tradition that settled across the Plains, and its close relations split mostly on shape and crimp rather than on filling. The bierock runs nearly the same beef, cabbage, and onion in a round bun sealed at the top. The Fleischkuekle takes the same impulse and fries a thin dough around the meat instead of baking it. Those are distinct sandwiches that share the runza's founding rule, a dough engineered to the cargo and closed all the way around, and each deserves its own article rather than being crowded in here.