Solo, Currywurst Stand (Konnopke's / classic Imbiss) works.
Grabbing a paper tray of currywurst standing at a classic stand is a cheap, fun, quintessentially-Berlin ritual, and Konnopke's under the Eberswalder tracks has been doing it since the GDR. The catch: it is, in the end, a cheap sausage with ketchup — fans of food experiences may find the hype outruns the plate.