Excellent bar-ish restaurant that is what British gastropubs should be like. The beer and wine are excellent and the food is superb. Short, uncomplicated menu (one starter, five main courses, two desserts). I particularly recommend the fish: last time I went I had halibut, which was superb. Eating perched on a bar stool is the way to go, don't worry about waiting for a table.
Oderbergerstr. in the north-centre of the city, just to the west of the 'wall route'. Nearest stations would be Eberswalderstr or Bernauerstr.