2 medium Vidalia or other sweet onions, each cut into 4 slices (about 1 1/4 pounds)
1/2 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
1 1/2 tablespoons balsamic vinegar
How to Make It
Prepare grill to medium-high heat.
Arrange mushrooms, gill sides up; bell pepper quarters; and onion slices on a baking sheet. Coat vegetables with cooking spray. Sprinkle evenly with salt and black pepper. Drizzle vinegar over mushrooms. Place vegetables on grill rack; grill 5 minutes on each side or until tender.