Use clean paper towels to blot the 4–6 lb prime rib roast until dry. Apply kosher salt and ground black pepper liberally. Allow it to sit and reach room temperature, roughly 1 hour.

In the meantime, in a small bowl, stir together 4–5 tbsp (56–70 g) softened butter or ghee with 2 tbsp fresh herbs. Coat the entire prime rib with this herbed butter. Set the prime rib on a sheet pan that has a wire rack, with the fat side facing up.

Set smoker temperature to 225°F (105°C).

Move the prime rib (still on the wire rack-lined baking sheet) into the smoker. Place a probe in the thickest section of the roast to monitor internal temperature. Smoke until the internal temp reaches about 118–120°F (48–49°C) for a medium-rare finish—be aware that a true medium-rare finish is 130–135°F (54–57°C), which will be achieved in the next step with the sear and resting time. This may take anywhere from 2 hours 45 minutes to 4 hours (or 35–40 minutes per pound).

Heat a large cast iron skillet over high heat and add 2–3 tbsp of the rendered fat/butter from the baking sheet. Sear the prime rib for about 2–3 minutes per side while spooning the rendered butter over it. Before taking it out of the skillet, check the internal temp again at the thickest part and confirm it is at or around 125–128°F (52–53°C). If it is not, keep searing 1 minute per side until it reaches that.

Take it out of the skillet and allow it to rest 15 minutes before carving—the internal temp will keep rising during this time.

Serve alongside prime rib horseradish sauce or some prime rib au jus.