Serves 10

Horseradish sauce:

- 1 cup light sour cream

- 3 tablespoons prepared horseradish

- 2 teaspoons country-style Dijon mustard

- 1/8 teaspoon white pepper

Prime rib:

- 1 (5-pound) fully trimmed rib roast of beef

- 1 tablespoon vegetable oil

- ½ cup finely chopped carrots

- ½ cup finely chopped onion

-½ teaspoon dried thyme

- ½ teaspoon salt

- Freshly ground black pepper to taste

- 2 cups rich beef stock or broth

- ½ teaspoon arrowroot dissolved in 2 teaspoons water

1. Prepare a horseradish sauce by stirring together the sour cream, horseradish, mustard and white pepper. Cover and refrigerate. Thirty minutes before serving, remove from refrigerator.

2. One hour before roasting, remove meat from refrigerator. Rub the exposed ends of the meat with oil and place in a roasting pan fat side up.

3. Roast in a preheated 325-degree oven for half an hour. Baste with the fat that has accumulated in the pan. Roast for an additional half hour. Place the carrots and onion around the roast and sprinkle with the thyme, salt and pepper. Continue to roast for about 1 hour and 15 minutes longer, or until the internal temperature reaches 145 degrees on an instant-read thermometer. Baste the roast occasionally with the drippings.

4. Remove the roast from the oven and let rest 10 minutes. Pour the fat from the pan and place pan over medium-high heat. Pour in the beef stock or broth, add the dissolved arrowroot and simmer 4 to 5 minutes, scraping up the caramelized juices in the bottom of the pan. Strain and keep the au jus warm.

5. Carve the roast and serve with the 2 sauces.

Adapted from “The Way to Cook” by Julia Child