Low Temperature Roast Beef

Ingredients:

1 standing rib roast (prime rib), 3-12 pounds (see note above)
Kosher salt
Freshly ground black pepper
Method:

1. Preheat oven to lowest possible temperature setting, 65°C or greater (some ovens can't hold a temperature below 100°C). 
2. Season roast generously with kosher salt and fresh ground black pepper. 
3. Place roast, with fat cap up, on v-rack set in large roasting pan. Place in oven and cook until center of roast registers 48°C on an instant-read thermometer for medium-rare, or 57°C for medium. In a 65°C oven, this will take around 5 1/2 to 6 1/2 hours. In a 100°C oven, this will take 3 1/2 to 4 hours.
4. Remove roast from oven and tent loosely with aluminum foil. Place in a warm spot in the kitchen and allow to rest for at least 30 minutes, and up to an hour and a half. Meanwhile, preheat oven to highest possible temperature setting (260°C to 290°F)
5. 10 minutes before guests are ready to be served, remove foil, and place roast back in hot oven and cook until well-browned and crisp on the exterior, 6-10 minutes. Remove from oven, carve, and serve immediately.