Spread a layer or two of lit charcoal briquettes on one-half of the charcoal grate. Position some wood chunks alongside the coals. On the opposite side, set up a tray of water, which will absorb some heat and release it slowly. After you have seasoned the roast, leave it to stand at room temperature for 30 to 40 minutes so that the outer ring of the roast won’t overcook before the centre reaches your ideal temperature on the barbecue.
Initially position the roast with the thicker end facing towards the coals.
An instant-read thermometer takes all of the guesswork out of cooking. For medium rare, remove the roast from the barbecue when it reaches the 48° to 51°C range, about 1½ hours for a boneless beef rib roast weighing about 2.5 kg. The internal temperature will rise another 5 to 10 degrees as the meat rests.