Here's a treat for those who like nothing more than an afternoon at the ball park. It's a casual meal but all the tastier for the modest amount of work involved, and it adapts easily to feed a crowd. The barbecued onion relish may remind you of certain stadium condiments, but it's head and shoulders better, and teamed with cheese and pickles, it transforms the brats into something sublime. It's also a lot of fun to make, with a little of this and a little of that tossed in. Start this major league meal with peanuts salted in the shell and cold beers, accompany the brats with potato chips and coleslaw and pass purchased ice cream bars for dessert.