Question: how do you cook a prime rib roast on a gas grill?
Answer: Combine the oil, garlic and spices in a bowl. Rub all over the meat. ... 
Heat the grill to 250F degrees with indirect heat.
Place the roast on the grill, fat side up. Cook until the internal temperature of the meat reaches 110F degrees, about 2 hours.
Raise the grill heat to 400F degrees. ... 
Slice and serve.