Allow roast to stand at room temperature for at least 1 hour.
Preheat oven to 375 degrees.
Rub roast all over with the salt, garlic powder and black pepper. Place roast on a rack in a pan with the rib side down and the fatty side up. Roast for 1 hour. Turn off oven. Leave roast in the oven but DO NOT open oven door for another 3 hours!
About 1 hour before serving time, turn oven to 375 degrees to reheat the roast.
Important Note: DO NOT remove roast or re-open the oven door from the time the roast is put in the oven until it's ready to serve!