1. Purchase a bone-in or boneless prime rib, planning for about 1 pound per guest.
2. Remove the prime rib from the refrigerator and let it come to room temperature for about 1-2 hours.
3. Preheat the oven to 250°F for a slow and even roasting process.
4. Season the roast generously with salt and pepper, or add additional seasonings as desired.
5. Place the prime rib bone-side down in a roasting pan or on a rack inside the pan.
6. Insert a meat thermometer into the thickest part of the roast, avoiding the bone.
7. Roast the prime rib in the preheated oven until it reaches an internal temperature of 120-125°F for rare or 130-135°F for medium-rare.
8. Remove the roast from the oven and let it rest for 20-30 minutes to retain its juices.
9. Increase the oven temperature to 500°F or use the broiler setting.
10. Return the roast to the oven for 5-10 minutes to create a flavorful crust.
11. Remove from the oven and let it rest again for about 10 minutes before slicing.
12. Slice the prime rib into portions and serve with au jus and horseradish cream if desired.
13. Enjoy your perfectly cooked prime rib as a delicious holiday or special occasion meal.