To improve the crust, allow the roast to air-dry, uncovered, on a rack in the refrigerator overnight before roasting.
Seasoning with salt up to a day in advance will help the seasoning penetrate the meat more deeply.
Preheat oven to lowest possible temperature setting, 150°F (66°C) or higher if necessary. (Some ovens cannot hold a temperature below 250°F/121°C.) Season roast generously with salt and pepper. Place roast, with fat cap up, on a V-rack set in a large roasting pan, or on a wire rack set in a rimmed baking sheet. Place in oven and cook until center of roast registers 120-125°F (49-52°C) on an instant-read thermometer for rare, 130°F (54°C) for medium-rare, or 135°F (57°C) for medium to medium-well. In a 150°F oven, this will take around 5 1/2 to 6 1/2 hours; in a 250°F oven, this will take 3 1/2 to 4 hours.
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 1 1/2 hours. Meanwhile, preheat oven to highest possible temperature setting, 500 to 550°F (260 to 288°C).
Ten minutes before guests are ready to be served, remove foil, place roast back in hot oven, and cook until well browned and crisp on the exterior, 6 to 10 minutes. Remove from oven, carve, and serve immediately.
is recipe works for prime rib roasts of any size from two ribs to six ribs. Plan on one pound of bone-in roast per guest. (Each rib adds one and a half to two pounds to the roast.) For best results, use a dry-aged prime-grade or grass-fed roast.
If, after step 1, your timing is off, and your roast is ready long before your guests are, reheat the roast by placing it in a 200°F (93°C) oven for 45 minutes before you continue with step 2.