To cook a great prime rib, or standing rib roast takes patience and timing. Other than that it is a very simple meal to prepare. Top it off with Yorkshire puddings and gravy and you truly have a feast set for any occasion. By taking your prime rib roast out to the grill you can add a great smoky flavor with a flavorful crust that makes it far better than oven roasting. The trick with grilling a prime rib is maintaining an even and constant heat. Gas grills help take care of this for you, but if you choose charcoal (which gives a better flavor) then you will need to add additional coals every hour.
A typical, bone-in, prime rib roast will cook at about 12 to 14 minutes per pound at a temperature around 325 degrees F. This means that a full seven-bone roast weighing in at about 18 pounds will take 3 1/2 to 4 hours. Always know exactly how many pounds you have before you start. Of course this rule is just a general guide. Always have an accurate meat thermometer ready to test the internal temperature and always take the temperature in at least two different places.
Prime rib must be left to rest after you remove it from the grill or oven. This allows the juices to seep back in and the flavors to continue to blend. It also allows the roast to continue cooking. The prime rib should rest in a warm (not hot), draft free place under a loose covering of aluminum foil. The roast will gain as much as 20 degrees while resting depending on the cooking temperature, size of the roast and the length of its rest. The rest period should be between 15 and 30 minutes. This gives you plenty of time to make gravy and get the rest of the meal ready before it's time to carve.
To carve a bone-in prime rib roast, start by first cutting bone side up, separating the meat from the bones. Then turn the pieces over and carve into thin slices. The thickness is a matter of personal taste. I prefer 1/2 inch thick slices for meals, but paper thin slices for the sandwiches you'll make the next day. This is one meal you'll want plenty of leftovers for.
So remember, be patient. The roast will take several hours to cook. The less you play with it while it's cooking the better. If you want your roast rare, remove it when the internal temperature reaches 115 degrees F. Let it stand for 15 minutes during which time its temperature should reach about 135 degrees F. If you want it more done, let it reach a higher temperature (no more than 135 degrees F) before you remove it from the grill and let it rest up to the full 30 minutes.