The Zelten sandwich is built on the principle that a dense sweet bread can be structural if it is met by something salty enough to answer it. Zelten is the spiced fruit-and-nut bread of the Tyrol and Alto Adige: a stiff dark dough heavy with figs, dates, raisins, walnuts, pine nuts, and almonds, bound with very little flour and seasoned with cinnamon, cloves, and often a splash of grappa or rum, baked into a low compact loaf that slices clean and keeps for a long time. Cut thin and laid against a salty cured meat such as speck or a sharp Alpine cheese, the bread stops being a sweet on its own and becomes the dense, fruited base that the fat and salt push against. The two need each other: the meat or cheese would be plain on a neutral bread, and the Zelten would be cloying without the salt to cut it.
The craft is in slicing the bread and respecting how little of it is wheat. A good Zelten is so packed with fruit and nuts that it barely holds together as a loaf, so it is rested until firm and cut thin with a sharp blade, because thick slabs eat heavy and sweet and overwhelm whatever sits on them. The cured meat is speck sliced fine so its smoke and salt read clearly against the spiced fruit, or a hard mountain cheese shaved rather than chunked so it does not turn the build into two dense things fighting. Nothing wet is added, because moisture turns the close fruited crumb to a paste and erases the contrast that is the entire point; at most a scrape of mountain butter bridges a very lean slice of meat to the bread. A sloppy build cuts the Zelten thick, piles the fill, and lets the sweetness bury the salt it was supposed to balance.
The close cousins stay in the Alpine larder and each deserves its own article rather than being crowded in here. There is Zelten eaten plain in thin slices with coffee as its own thing, the same spiced loaf served against a wedge of blue or aged cheese as a cheese-course pairing rather than a sandwich, and the Brezel with speck which solves the bread-against-cured-pork problem with a bitter lye crust instead of a sweet fruited crumb. Each is a different bread argued against the same mountain shelf, and each is its own subject.