Try this method and you'll never use your oven again. The turkey cooks in half the time recommended for oven roasting, and it remains moist and juicy with just one basting. But stifle the impulse to open the grill lid for a peek – the heat in the grill will drop significantly and slow your cooking.
Preheat gas grill for 10 minutes with all burners on low heat (400 degrees F). Rinse turkey and pat dry. Stuff turkey with Herb Stuffing (see recipe). Coat skin of turkey with olive oil spray or brush skin with oil. Season skin with salt and pepper. Place turkey in a disposable aluminum foil roasting pan coated with cooking spray. Create a tent of aluminum foil over the turkey and seal tightly. Place pan on the grill rack and close lid. Cook 3 hours (for a 20-pound turkey) or until popper is exposed or turkey leg can be pulled away from the body. Remove tenting. Baste turkey with drippings (remove 3 tablespoons drippings for gravy). Close grill lid, raise heat to medium, and cook 15 minutes more or until bird is golden brown. Remove turkey from grill. Allow bird to sit 10 minutes. Remove dressing to an ovenproof bowl and place it in a warm oven until serving. Carve turkey, place on a large platter, and serve.