Preheat your Kamado Joe (or other smoker) to 250 degrees F. Load the smoker with cherry or apple wood.
**Optional. When preheating the smoker, I like to cook the prime rib for a few minutes on each side in a hot cast iron pan. Not necessary but adds a little something extra!
Place the mustard, Worcestershire sauce, onion, garlic, thyme, rosemary, salt and pepper in a bowl. Stir to combine.
Rub the mixture all over the roast.
Once the smoker is at temp, place an aluminum foil pan under where you plan to put the roast.
Place the roast in the smoker. Cook until a thermometer registers desired level of doneness (I like to cook to 125 degrees F). See temp chart above.
Remove the roast from the smoker and cover with foil. Let stand for 15 minutes. The roast will continue to cook during this time and the temperature will rise another 5 degrees.
Cut into slices and serve immediately with au jus.