Choose a well-marbled bone-in rib roast.
Rub Kosher salt and black pepper over the entire rib roast coating the sides, top and bottom. Refrigerate uncovered for 1-2 days. This will help the meat retain moisture.
Set oven to 250°. Place the roast on a rack in a pan.
Roast in the oven until the temperature reaches about 125° for a rare/medium doneness.
When the meat reaches 125°, remove it from the oven and tent with aluminum foil. Let the roast rest for a minimum of ½ hour and up to 1½ hours.
Heat oven to 500° to 550° and return the roast to the oven for 15 minutes. This will provide a nice sear to the top of the roast and the inside will be evenly cooked.
Let the prime rib sit a few minutes, remove the bones and then slice.