Jus is the French word for meat juices. Start with beef or chicken stock (preferably homemade). Add the cutting board juices before serving.
Step 1: Place the stock in a small foil drip pan next to the prime rib in the smoker. Smoke it while you smoke the prime rib.
Step 2: Strain it into a saucepan or serving bowl and keep warm until serving. Pour any meat juices that accumulate on the cutting board into the jus and serve.