If frozen, thaw in its packaging on a tray in the refrigerator; it will take 24 hours for each 4 pounds (figure 3 to 4 days for a 15-pound bird).
When thawed, unwrap and remove giblets and neck; rinse inside and out with cold water. dry turkey, including both cavities. tuck wings under, if desired. Season as recipe recommends.
Roast at 350 degrees F for 12 to 15 minutes per pound or until instant-read thermometer inserted in thickest part of the thigh registers 180 degrees F, 160 degrees F in the breast.
Transfer to platter; let rest 20 minutes before carving.