The first step for the perfect Bratwurst is to fire up your grill and get a couple of gallons of beer on boil. I have perfected my own technic over the past 8 years, I think it is pretty good anyway.

Pour 2 gallons of beer into a large pot or something, bring to a boil. Peal and put in 1 large whole onion, 4 tablespoons of dijon mustard, 1 teaspoon of balsamic vinegear, and 4 table spoons of whole pepper corns.

Bring it all to a boil again, let it boil for 5 minutes then reduce heat so it is near boiling but not really boiling, a slow cooker or crock pot actually works pretty well for this. Let it almost-boil for at least 1 hour.
Fire up the grill, ultimately we just want medium heat, but I alwys suggest heating it way up first then let it calm down.

Never do more than 5 brats at the time - put 5 in the almost boiling beermix - let it soak and cure for 10 Minutes exactly. When it floats it is VERY near ready. Do NOT cook dry!
Put on the grill, 3 minutes on each side, then dip 5 seconds in the beer and it is now done! Server with raw hot-peppers!