Remove the prime rib from the refrigerator and let it sit at room temperature for 30 to 60 minutes
Preheat the oven to 250°F to 300°F
Place the prime rib in a baking dish or on a rack in a roasting pan
Add a small amount of beef broth or water to the pan if desired
Cover the meat loosely with foil
Heat until the internal temperature reaches 110°F to 130°F for medium-rare to medium
Check the temperature with a meat thermometer
Remove the prime rib from the oven and let it rest for 10 to 15 minutes
Slice and serve immediately
Reheat only the portion you plan to eat to avoid overcooking
Avoid using high heat or the microwave if possible