Searing is a method of cooking meats at a high temperature to seal in the juices and flavor. Searing a prime rib also allows you to achieve the traditional rare interior. The key to a perfect prime rib it to cook it on high heat for a short amount of time then spend the rest of the cook time at a substantially lower temperature. The lower temperature actually draws out the juices, creating a moist and tender cut of prime rib.
Preheat the oven to 450 degrees Fahrenheit and put the rack at the center setting.
Let the meat sit out for two hours to get to room temperature. The meat will not sear properly if you start with it straight out of the refrigerator.
Mix the butter, garlic and salt together, and use your hands to rub the butter into the rack of prime rib. Put the meat into the roasting pan, rib-side down. The ribs will act as a natural rack to support the meat.
Insert a meat thermometer into the thickest part of the meat, and put the meat in the oven for 20 minutes. The heat of the oven will sear the meat.
Turn the oven down to 325 degrees Fahrenheit and roast until the internal temperature reaches the desired level of doneness: 110 to 115 degrees for rare, 120 to 125 for medium-rare and 130 to 135 for medium.
Remove the meat from the oven, and transfer it to the serving dish. Let the meat rest for up to 30 minutes. The meat will continue to cook for several minutes after you remove it from the oven. Letting it rest allows it to finish cooking and the juices to fully infiltrate the meat.