Remove the roast from the refrigerator 3 hours before cook time. Sprinkle with half the salt and let stand, loosely wrapped in parchment paper. (Bringing the roast close to room temp helps to ensure more even cooking.)

Tie roast with kitchen string. Cut bones away from the roast and tie back on to the roast with kitchen string. (This facilitates carving)

Preheat your oven to 500°F. Pat roast dry with paper towels. Sprinkle the roast all over with remaining salt and fresh pepper.

Place roast fat side up and rib bones down in roasting pan. Insert an oven-proof meat thermometer into the thickest part of the roast.  Make sure the thermometer isn't touching a bone.

Roast for 15 minutes at 500 F.Reduce the oven temperature to 325°F and cook to desired temperature. Allow 11-12 minutes per pound for rare and 13-15 minutes per pound for medium rare. Thermometer should register 115°F for rare or 120°-130°F for medium. Remember, the internal temperature will continue to rise after you take the roast out of the oven. (Example: A 10 pound roast will take approximately 2 hours of total cooking time for rare - 15 minutes at 500 F and 1 3/4 hours at 325 F.)

Remove roast and place it on a carving board. Cover it with foil and let it rest for 30 minutes before carving. The internal temperature of the roast will continue to rise while the roast is resting.

Cut strings, remove bones and slice roast against the grain, making the slices about 1/4-1/2 inch thick.

Note on Servings: A prime rib will serve roughly 3-4 people per "rib". So a 3-rib, 5 lb. roast will serve 9-12 people.