I haven't been there in a few years, but I was very impressed by
Kolja Kleeberg's Restaurant Vau - try the pigeon breast with
celeriac julienne. If you want to show your savoir faire around the
cream of society (I've never been interested in that and have never
been there - this is only hearsay), try the restaurant Adlon at the
Hotel Adlon.

For arts-conscious folks or Francophiles, Ganymed, where Kurt
Weill and Bertolt Brecht used to eat, is very enjoyable, and the
selection of schnapps, although not large, is discerning.