Preheat grill to 350° to 400° (medium-high). Cut onions into 1/2-inch-thick slices. Brush with 2 Tbsp. Fresh Herb Vinaigrette. Grill onions, covered with grill lid, 10 minutes on each side or until crisp-tender. Sprinkle with salt and pepper to taste. Serve with remaining Fresh Herb Vinaigrette, if desired.