I can't answer about street food because I don't do that except for fish-n-chips when I vacation in Scotland. Here in Swabia I have yet to try saure Kutteln (sour tripe), but I'd say that qualifies as unusual. My mother-in-law had to make brain soup for her daughter for a while when she was growing up because of some health problem she was having. I don't think I need to try that, but again - counts as unusual to me.
At our house typical breakfast for me is coffee, and for my husband coffee and a cigarette. When I'm trying to impress guests I do the typical German style: fresh bread and Brötchen, sliced Wurst/Schinken/Salami & cheese, juice, Marmelade & honey, and coffee.
Our favorite dishes (we both love to cook): Rehrücken (venison tenderloin) with a herb-nut crust, Züricher Geschnetzeltes (pork tenderloin in a cream sauce) with Rösti, like American hash browns, lamb stew, grilled pork tenderloin with potatoes gratin or Bratkartoffeln... Clearly we are not vegetarians, but when I dine out I very often order Kässpätzle (cheese Spätzle). I have found many of the recipes we make in the little free weekly magazine our local butcher provides.
Essential ingredients in German cuisine - nutmeg. We/They put nutmeg in nearly everything. And pork and potatoes, of course. But what makes German cuisine unique to me is their seasonal focus. Right now, chanterelles, in Spring white asparagus, in fall wild game and pumpkin, etc.
We live in a tiny town (pop. 1800) where there is a fabulous restaurant run by a local boy. He is a brilliant chef, and always has offerings that are vegetarian, vegan, gluten-free, lactose-free... If you tell him your special needs, he will cook something fabulous for you. He has an open concept kitchen, so you can watch him cook as you dine - it's like dinner and a show. He also has seasonal menus, as every decent German restaurant does, and I'm looking forward to "Wild" season; the wild game he cooks comes from our local forests.
One last comment about German restaurants. I'm from the midwest of the US, and since moving here 7 years ago, I don't like going out to eat "back home." Restaurants are chains, and the food tastes like it arrived frozen on a truck and was just heated up, which is probably the case. In Germany most restaurants are family-owned, and often it's been the same family for generations. The restaurants have atmosphere and old-world charm. When I ask the server to recommend a wine, s/he knows what "dry white" means and what wine would go well with what I'm ordering. In the US you better know exactly what type of wine you want (i.e. Pinot grigio or Merlot) because the server likely won't have a clue ("We have both kinds - red and white.") :-)