I have ccoked literally tons of Prime Rib in my lifetime. I am in the "food" industry. YES do cook at a high temp to seal or sear in the juices. I do not typically go as high as 550 , but use 500 as my starting point. I do this for approx 20 minutes to 25 minutes ( this is largely depending on the BTU's of the oven). ( note : the fat lip should be on top, bones on the bottom) Once you can see a the outer portion is seared or completely browned to about 1/8 inch deep . Leave the roast in the oven ... but turn it down to 250-275.. the temp will "drift" down to that point. This is now the slow cooking part . Cook till it reaches 135 on the meat thermeter. This will produce a rare to medium rare roast. Do not carve for at least 10 minutes . The temp will gently rise a bit higher ( rare is between 135 -140 ) , but the juices will be retained more with in the roast when carving. If you cook till 140 the roast will continue to cook and the results will be more medium/to medium well.
One note : cooking this method does produce less drippings for gravy, but there will be some shed during the carving. So use some type of carving pan that allows you to capture those juices for gravy or an au jus.
Retain the bones , as you may want to use them for soup.... they do make the best beef stock for french onion soup.
Last edited by Lori S; 12-20-2011 at 05:26 PM.