Splitting a Prime Rib Roast Question
I have a 13 lb choice standing rib roast that I am roasting for Christmas. Given that 1/2 of the people at the dinner like medium to well and the others like rare-medium rare, I am wondering if I should just split the roast in two and start on one of the roasts, 20 minutes (or so) before the other one. Or, I can just cook to medium rare in the center and hopefully the ends will be more "well". Any insights?
First remove the roast 1-2 hours out of refrigeration in advance of roasting....Your going to need five hours roasting time to finish both roasts....assuming you can fit both in the oven at the same time.
Split your roasts in the middle and season both separately. If possible, if can can tie string around them, as it will make for easier removal from the roasting pan.
In a pre-heated 450^ oven, 5-6 hours before you intend to serve, place both roasts on a rack, in a shallow roasting pan and place in the oven for a 15-20 minute browning phase @ 450*. Drop the oven temperature setting to 225* for about 2.5 hours and make your first check to see where one roast is progressing towards your target temperature of 122*....it may be on the mark, close , or it may take another hour. Once the first roast hits the target of 122*, remove it from the oven to begin the holding phase for it. The easiest way for you to hold the roast without too much loss of heat is to put it in an insulated food/beverage cooler, wrapped in foil, or not. You will be holding this roast until the second roast hits it's target temperature of 140-145*
Continue roasting the second roast until it reaches 140-145*, which should take at least another hour....or around the 4 hour mark of roasting. When the second roast hits the target temperature, reduce the oven temperature to 140*, or the lowest warming setting. If it's above 140*, then you can crack the oven door while holding to let some heat escape.
At this point, take the first roast and replace it back into the oven with the second roast. If you were able to tie the roast as suggested, you can do this easily with the string. Now you are holding both roasts for another 60 minutes....or until you are ready to serve.
When you are ready to serve, and both roasts in the oven, increase the oven temperature to 450* for another 10 minutes. Remove both roasts from the oven and you are ready to slice.
Keep in mind, the first roast will rest for about two hours and the second roast for about an hours time.
You're looking for a range from rare to well. I don't think that can be done with a single roast. The link Sal Vanilla provides below is all well and good for a rare roast, but isn't going to accomplish what you need. I think your instincts are exactly right. Divide the roast, put one part in first with the second to follow. It's really the only way you're going to make all your guests happy.