This is an awesome technique for any large roast without skin (read: no poultry). It is perfect for the standing rib roast and other large roasts such as pork ham or beef tenderloin. It’s really pretty simple. Essentially, you’re going to slow cook first then remove the cook long enough to let the internal temp stop rising and heat your grill up to searing temperatures.
First, prep your roast to your liking, being sure to bring the piece of meat to room temperature before applying any cooking heat.
Put the roast on an indirect cooking surface at about 225 degrees (on the Egg use your plate setter with the feet up). One thing you’re going to notice is that you hardly have drippings. Use some sort of drip pan if you hope to save them for later gravy/sauce making. As the internal meat temperature rises very slowly it doesn’t release nearly as much moisture so the roast will stay much juicier for later.
When the internal temperature reaches about 105 (for a rare finish after carry-over and searing) to 115 (for a medium finish after carry-over and searing) take the roast out of the grill and let it rest, uncovered in a room temperature area. Use a temperature gauge so you can watch the internal temperature. You want to let it rest until the internal temperature stops rising, it’s common for it to rise another 15 degrees while resting.
Raise the cooking temperature of your grill to 525 degrees.
Once the internal temp on the roast stops rising and the grill is preheated, put the roast back in the grill for 30 minutes. If your cooking temperature drops below 525 for more than 5 minutes then add that to the searing time. You want 30 minutes at 500 or higher. You will notice that your internal temperature barely changes during the sear cooking period, usually about 3 degrees.
After the 30 minute sear, remove the roast and let it rest again for about 30 minutes, uncovered. The internal temp should rise to your target range of 125-145 (depending on the temperature at which you took it off the grill the first time). It rises very slowly so be patient and enjoy the time before your big meal.