Over at Dummocrats, the great bratwurst controversy is on. For the record, I prefer Klements to Johnsonville, and I prefer small butcher shop brats to either. Onions, Sauerkraut, Mustard and Secret Stadium Sauce (available in most grocery stores) are the essentials, though occasionally a kosher dill spear is a good adder.
To prepare, I prefer a stronger beer, no water, some onions, then simmer on the stove until nearly done before you brown them on the grill. Miller Lite is for consumption not for cooking. Leinenkugel works real well for cooking brats.
Sides should be limited to chips, potato salad, and baked beans.