Growing up on a lake in the Sheboygan area, this was a standard way that the German folks would grill their brats. We always served them on the old-fashioned hard rolls. By finishing them in the beer sauce they just get better and better. Though it's expensive, on special occasions I use a dark beer which is not German at all: Guinness Irish Stout. Around our house, we eat them with ketchup and mustard, and the cooked onions from the brat sauce.