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Sear the rib roast (prime rib) for 15 minutes at the higher oven temperature (450 degrees F.), then turn the oven to the lower temperature (325 degrees F.) for the rest of the cooking time. Every 1/2 hour, baste the cut ends of the roast with the fat accumulated in the roasting pan. Do Not Cover the roast.rime Rib Roast (standing rib roast), at room temperature (very important) 2 tablespoons butter, room temperature. Preparation: Preheat oven to 450 degrees F. Pat the room-temperature standing rib roast (prime rib roast) dry with paper towels or napkins.
Grab a shallow pan and place the prime rib in it with the bone side facing down. Roast it at 450 degrees F for 15 minutes to sear the outside, and then turn the oven down to 350 degrees F. Continue roasting the prime rib for 45 to 90 minutes, depending on how done you like your meat. Check it by inserting an instant-read thermometer in the meatiest part of the roast.