Parboiling bratwurst in beer or seasoned water before grilling adds flavor and ensures that brats remain plump and juicy after grilling.
Place bratwurst, beer, cloves, and onion in a large pot and bring to a boil.
Reduce heat and simmer for 25 minutes.
Heat charcoal or gas grill to medium-hot (coals should be white, not flaming).
Place bratwurst on grill and cook for 10 minutes, turning often. Spraying with water or beer a few times while cooking will make brat skins crispy.
Remove from heat and serve with brown mustard.
Bratwurst can be boiled at home, then grilled at your tailgate party location. Of course, you can always cook brats completely on the grill, but do be careful to avoid flare-ups, and turn them often.