Expert: Steve Hanagan - 2/12/2008

Question
I have a dinner party this Saturday for 55-60 people. WE want to serve prime rib med. rare and medium only. How many pounds do I need. We plan to eat at 6:30p.m. How long do I need to cook the roast, at what temp. and also a really good seasoning or rub. thanks

Answer
For the usual mixed crowd of eaters you should usually plan on about 1/3 pound per person, assuming this is boneless.  (Since I suspect you will be working with limited oven space, plan on using boneless roasts.)  You are likely to need two or three roasts, depending on their size, but a total weight of about 20 to 22 pounds should do fine.

As far as seasoning, you can’t go wrong with a simple combination of  Parsley, Thyme, and Marjoram, in equal parts, to a half part each of Garlic Powder and Salt, and Pepper to your liking.  If you like, you can lightly coat the roast with olive oil and a bit of Kitchen Bouquet to darken up the meat a bit before adding the herbs.  (Kitchen Bouquet is a dark seasoning agent used for soups and for browning.  A little bit goes a long way, and it can be messy, so be careful.)

Because of the volume of meat you will be cooking, I’d suggest using two ovens if at all possible and cook them at 325 F. I do not ever cook a roast by “time,” rather based on internal temperature.  Plan on using an internal thermometer, preferably one that can stay in the oven as the meat cooks.  (Precise times are impossible to give because I don’t know the size of the meat, how well the oven holds its temperature, whether the oven runs hot or cold, etc.)

Not knowing the size of the roasts, it is even difficult to give you an estimate on the time other than to say that typically for a large roast you can count on 11 to 13 minutes per pound at 325 degrees. (Note:  If you have more than one roast you don’t simply add the weight together and multiply by 11 or 13, but how to come to an estimate depends on the size and how many ovens you will be using.)   Once you have the roasts, feel free to submit a follow up question and let me know about the ovens as well and I’ll give you a better estimate and work backwards from there and figure out when you should start the roasts.   

For Medium Rare, you want to pull the Roast from the oven at 133 degrees internal temperature. Allow it to sit 15 minutes, then carve it.  This allows the carry over cooking to take it to 140 to 145 degrees  and to allow the juices time to stabilize in the roast instead of running all over the cutting board.  The longer you let the roast sit beyond 15 minutes, the more it will continue to cook.   At 30 minutes resting, you are looking at well-done.  (Keep this in mind when you are slicing, as the longer they sit, the more they will cook.)