Ingredients
2 teaspoons olive oil, plus more for grill
2 large red onions, each sliced crosswise into 4 rounds
1 tablespoon white balsamic vinegar
5 tablespoons whole-grain Dijon mustard
Coarse salt and ground pepper
2 pounds boneless pork loin, sliced into 8 equal pieces
Preparation
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.
