Like a "london broil", a "prime rib" is a marketing term to sell meat. A "prime rib" roast is a standing rib roast.
Order your standing rib roast well in advance. Talk to your butcher (he or she is a nice person). I like to specify USDA Choice for a standing rib. You may or may not be able to order this, as many meat wholesalers market under their own terms and names. Even with select grade meat, the rib roast should be tender and well marbled with fat.
For every two people you will be feeding, you need a rib. Don't get anything smaller than a 3-rib roast, through. You can also figure on about eight ounces per person. Request a small end rib roast. The ribs of a steer get larger as you move from the front towards the back. The larger the bone, the smaller the section of meat in the middle. Request "three ribs off the small end", or as many as you need.
Ask your butcher remove the chine bones, feather bones and back strap. It probably will already be done, but ask - it will make carving easier.
To cook the roast, you'll need three things: A big pan, a big rack, and an accurate thermometer. The whole roast should fit inside the pan without touching the metal anywhere. The rack should keep the roast an inch or so above the bottom.
First, figure on how much time you'll need. You can figure about 18 minutes per pound, although this is only a very rough guideline. That rule can tell you when to put the roast in; to know when to take it out, use your thermometer.
|Standing Rib Roast Temperatures|
|120°||Very rare (bloody, or "bleu")|
Secondly, take in consideration the fact that the roast must "set up" before carving. This allows the jucies to go back into the meat. A roast cut hot from the oven will spill most of its juice onto the carving board. Just take the roast out, cover it very loosely with tented foil, and leave it on the counter for half an hour. It will still be plenty hot when served.
For example, say you want to serve the roast at 5:00 pm. You want it medium (internal temperature of about 140°). The roast weighs 8 pounds. Therefore, you need about 8 x 18 minutes or 144 minutes -- say, two and a half to three hours. Add half an hour for setting up, and you know you need to start the roast at 2:00 pm. It does not tell you to to take it out at 5:00.
Due to differences in cuts of meat, oven temperatures and other factors, actual cooking times vary. You must rely on a thermometer for knowing when to remove the oven.
The best kind of thermometer is the instant read type. This will tell you the exact temperature within ten seconds or so; you put it into the roast, check the temperature, and remove it. These are reliable and fast. Otherwise, use a standard meat thermometer. These you insert into the roast at the beginning of cooking time. Make you you insert it into meat, not fat, and not touching bone. Also, make sure you can easily read the display when you open the oven.
Rub the surface of the roast with plenty of kosher salt salt and coarsely ground black pepper. If you wish, insert slivers of garlic into small cuts made into the fat and meat.
Put the roast on the rack and put it into a 325° oven. Don't cover the roast or marinate it with any kind of liquid.
Start checking the temperature well before the time your chart tells you to remove it. You'll want to pull the roast about 10 degrees under your target temperature.
For example, say you want a medium (140°) roast served at 5:00 p.m. At 4:00 the internal temperature reads 132°. Go ahead and take the roast out. Put it on the counter, cover it with the tented foil (make sure any steam can go out the sides) and leave it near the oven. The roast will remain hot enough for serving for nearly an hour. There will be no problem with food safety leaving a cooked beef roast out for this period.
During the time the roast sets up, the heat in the beef will continue to cook the meat. It will rise easily to 140o and past it before starting to cool off. Taking a roast out of the oven when the internal temperature is 140o will insure a well done roast, so be pre-emptive.
Finally, a few words on well done or rare: Some people like their meat bloody. Your target temperature for this would be 120°. Others feel queasy when they see any pink in their meat; cook the beef to 170° for these people, although beware -- a well done prime rib is, in my opinion, a waste of a fine cut of meat. In fact, the pink color of meat will be gone by 140o - 150o. Anything more is just drying out the meat.
To carve the roast, cut away the ribs and layer of fat that hangs beneath them. Turn the roast on it's side, and simply slice out slices as thick as you like them.