Step 1

Remove the roast from the fridge 2 hours before cooking and season with salt. Pat the roast dry with paper towels and season generously with the salt, being sure to coat the sides, ends, and the ribs below. Don't worry about using all the salt. Place the roast in a roasting pan or 9x13-inch metal baking pan with the ribs in the pan and the fat cap up. Leave at room temperature for about 2 hours.

Step 2

Make the horseradish sauce (optional). Place all the ingredients in a medium bowl and whisk until smooth. Cover and refrigerate until ready to serve.

Step 3

Heat the oven to 500°F. Arrange a rack in the middle of the oven and heat the oven to 500°F.

Step 4

Oven-sear the roast for 15 minutes. Place the roast in the oven for 15 minutes. Be prepared — during this time, the roast is going to put off a fair amount of fat and there will be smoke. Turn on your stove or oven's vent and open a few windows. Don't worry, the roast will be done with smoking after this and your kitchen will be smoke-free long before guests arrive for dinner.

Step 5

Reduce the oven temperature to 325°F and cook for 13 minutes per pound. Drop the oven temperature to 325°F and continue to cook the roast for at least another hour before you begin checking the roast's temperature. Larger roasts can take a total of 1 1/2 to 2 hours. Cook the prime rib to 115°F for rare and 120°F to 130°F for medium — remember that there will be carryover cooking as the roast rests.

Step 6

Rest the roast before carving. When the roast has reached your desired temperature, remove the roast from the oven and transfer to a clean cutting board for carving. Cover in aluminum foil and rest for 30 minutes.

Step 7

Carve the roast. Use a pair of shears or a knife to cut away the twine. Pull the prime rib roast away from the bones, and cut into 1/2-inch-thick slices. Serve with plenty of horseradish cream or gravy.