Excuse me but I still dodn't get the answer what's a trademark of German cuisine. In Poland people associate German cuisine with a leg of pork with a beer - nothing sophisticated, typically razzle-dazzle kind of dish. Austrian cuisine is a different story though.
So what kind of dish would you suggest me if I ever were to visit a German restaurant?
German cuisine is a bad as Polish, Dutch or Skandinavian... simply the wrong latitude for good food.
If you want something German stick to bread, sausages and cakes, everything else sucks, so the best tip is to go to a bakery.
In a restaurant you should try "Rouladen" and Thuringian dumplings (Kloesse), a simple Schnitzel and Bratkartoffeln (home fries) or Bauernfrühstück (better version of Bratkartoffeln). There are some good, sophisticated dishes, like Leipziger Allerlei, but in America you don't get them anyway.