Rinse your roast under cold water. Pat dry with paper towels and place roast on wire cooling rack. Salt all sides of the roast with coarse sea salt and place in the refrigerator for 3 days.
Preheat your grill to 225°F.
While the grill is preheating, prepare your prime rib by applying a light coat of olive oil over the entire roast.
In a mixing bowl, whisk together all ingredients for the beef rub. Apply liberally over the entire roast. On top of the beef rub, sprinkle chopped fresh rosemary. Allow roast to sit on the counter and come up towards room temperature while your grill preheats.
Insert a reliable meat thermometer in the roast, place roast on grill over indirect heat, as far from the heat source as possible. Be sure to place the roast with the bones facing the heat source.
When the internal temperature reaches 120°F (about 2 hours), remove the roast from the grill and set aside. Increase the direct heat zone of your grill to as hot as possible.
Place the roast directly over high heat for a total of 5 minutes, turning often so built a crust.
Remove roast from heat, place on a cutting board, and tent with foil. Allow resting for 10–15 minutes before slicing.
Using a sharp knife, slice roast in 1/2 inch slices and serve with roasted garlic mashed potatoes and creamed spinach.