Heat oven to 450 degrees F.
If prime rib is not seasoned, sprinkle with salt, pepper, minced garlic, ginger, and mustard powder.
Sear all sides in hot skillet.
Place on rack, in shallow pan, with fat side up. Insert meat thermometer in thickest part of meat, but do not rest on bone. Roast for 30 minutes.
Reduce heat to 325 degrees F and roast another 2 hours.
In a small saucepan, combine the ingredients for the Au Jus and simmer until prime rip is ready.
Interior should be 155 for medium rare.