Step 1: Generously—and I mean generously—season the roast on all sides with salt and pepper, and with onion and/or garlic powder, if using. Rub the seasonings into the meat. Drizzle the olive oil over the roast and rub it into the meat as well.
Step 2: Set up your smoker according to the manufacturer’s instructions and preheat to 250°F (this is on the higher end of the smoker scale). Add the wood as specified by the manufacturer.
Step 3: Place the roast in the smoker directly on the rack, bone and fat side up, inserting the probe of your remote thermometer through the wider portion of the meat. (If you do not have a remote thermometer, periodically check the temperature of the meat with an instant-read meat thermometer.)
Step 4: Smoke the roast until the exterior is sizzling and darkly browned and the internal temperature of the meat is about 110ºF (about 2 hours).
Step 5: Transfer the roast to a platter. Increase the heat of your grill or smoker to 400ºF.
Step 6: Indirect grill the prime rib on all sides until the crust is sizzling and browned and the internal temperature is 120° to 125°F (for rare; 130° to 135°F for medium-rare). Remember, the roast will continue to cook as it rests.
Step 7: Transfer the roast to a cutting board with a groove and a well to catch the juices (or place cutting board on a rimmed sheet pan) and loosely drape a sheet of aluminum foil over the meat. (Do not bunch the foil around the roast or you’ll steam it and make the crust soggy.) Let rest for 10 to 15 minutes. This “relaxes” the meat, making it juicier.
Step 8: To carve the prime rib, slide a long sharp knife down the inside of the rib bones to loosen the cylindrical eye of the roast. Lift away the bones and cut the meat crosswise into 1/4-inch-thick slices, or however thick you like. Then slice the rib section into individual bones. Good luck on figuring out who gets them.
Serve with Three Hots Horseradish Sauce.