Herb Crusted Prime Rib Roast

In a food processor, combine the rosemary, parsley, garlic, olive oil, spicy mustard, salt, and pepper. Pulse until the herbs are finely chopped and the ingredients are combined. Coat the entire prime rib with the herb mixture. Refrigerate uncovered for 4 hours. Preheat grill to 250F. Insert a probe into the thickest part of the roast. Place the prime rib on the grill grates. Insert the probe into the thickest part of the roast, avoiding the bones (if you have a bone in roast) and any large pockets of fat. Close the lid and cook until the internal temperature reaches 120℉-130℉ for rare to medium-rare, about 3.5 - 5 hours depending on the roast. Remove from grill and rest for 15 minutes. Slice. Serve.