I do mine somewhat similar to bikeage, but with an added little twist that has become hugely popular with family & friends. It's a bit more work, but worth it. I make 2 beer baths. The first is just beer, large chunks of onion, and butter. This is for when the brats come off the grill. The second is beer with onion, garlic, green pepper (and sometimes red and yellow peppers), diced as finely as I possibly can. This is where I pre-boil the brats for a bit. I leave this boiling madly while the brats are on the grill. When it's boiled down to no liquid left, and everything is brown and carmelized, I strain it through a wire strainer. This becomes relish for use on the finished brats. It is fantastic! The only thing you need to watch, is to not use too much green pepper or it will overpower everything else. There's no such thing as too much onion or too much garlic though. Yummy!