Place turkey breast side up on a sheet pan. Liberally rub butter-herb mixture completely over entire turkey. Refrigerate 24 to 48 hours uncovered.
Remove turkey from the refrigerator and bring to room temperature while your grill or smoker is reaching 225 degrees.
Oil the rungs of the rack to keep the bird from sticking.
Bring either the grill or smoker to 225 degrees. Add several chunks of hickory or apple wood (they burn more slowly and won’t overtake the flavor of the turkey) to the smoker or on top of the charcoal if using a grill.
Place turkey in the middle of a smoker or on the grill preheated to 225 degrees. Maintain temperature between 225 to 250 degrees during entire cooking process, 2 to 2 1/2 hours depending on the size of the bird. Account for 11-13 minutes per pound.
Once the bird reaches 160 degrees, remove from the smoker and cover loosely with foil and allow to rest 30 minutes before carving.