Mustard-Coated Pork Chops and Onions

Heat grill to medium; lightly oil grates. Coat onion slices with 2 teaspoons oil. Place on grill. Cover; cook, turning once, until slices are charred in spots, 6 to 8 minutes. Transfer to a piece of foil; return foil with onions to grill. Cover, and continue cooking until tender, 10 to 12 minutes more.

Transfer onions to a bowl. Toss with vinegar and 2 tablespoons mustard; season with salt and pepper. Cover to keep warm.

Coat pork with 2 tablespoons mustard; season with salt and pepper. Place on grill. Cover; cook, turning when grill marks are visible, until meat is no longer pink in the middle, 6 to 10 minutes. Brush with remaining tablespoon mustard. Serve with grilled onions.