- 1 (5-lb) bone-in standing rib roast (prime rib)
- sea salt and freshly ground black pepper
- 8 Tbsp (1 stick) butter, softened
- 5 cloves garlic, mashed or crushed into a paste
- 1 Tbsp dried Italian herb blend
- 3/4 cup sour cream
- 3 Tbsp peeled and freshly grated horseradish or prepared horseradish
- 1 Tbsp fresh lemon juice
- The day before you plan to prepare the prime rib, place it on a baking sheet and salt all the meat surface with 4 teaspoons of salt, then refrigerate, uncovered, overnight.
- The day of cooking, remove the beef from the refrigerator and bring to room temperature, 2 to 3 hours. Pat the beef dry with a paper towel.
- Preheat oven to 475°F (245°C). Adjust the oven racks so the beef can roast in the middle of the oven.
- In a small bowl, mix together the butter, garlic, and dried herb blend. Season with 2 teaspoons salt and 1 teaspoon pepper.
- Slather a layer of about 1/3 of seasoned butter on the underside of the beef (the bone side). Place the beef in a heavy ovenproof skillet or roasting pan, bone side down. Spread another 1/3 of the remaining seasoned butter on the top and sides, reserving the remaining butter for the first baste.
- Roast for 20 minutes. Reduce the oven temperature down to 275°F (135°C), spread the remaining seasoned butter over the top of the beef, then continue roasting, basting every 30 minutes with pan juices, until the internal temperature is 120°F (50°C) for medium-rare, about 90 minutes. (Start checking the internal temperature early in case it cooks more quickly.)
- Transfer the beef to a serving platter, cover loosely with foil, and let it rest for 25 to 30 minutes; the internal temperature will rise to 125°F (52°C).
- Meanwhile, make the horseradish crème: in a medium bowl. Combine the sour cream, horseradish, and lemon juice. Season with 1/2 teaspoon pepper.
- Slice the beef and serve with the horseradish sauce.