Ingredients:

  • 9 lb Bone-in Prime Rib (3-4 bones)
  • 30g Kosher salt
  • 15g Coarsely cracked black pepper
  • 5g Dried thyme
  • 40g Softened unsalted butter
  • 2kg Yukon Gold potatoes, peeled and quartered
  • 8 cloves Garlic, smashed
  • 250ml Heavy cream
  • 115g High-fat European butter, unsalted
  • 10g Fine sea salt
  • 5g Freshly cracked white pepper
  • 240ml Sour cream
  • 60g Prepared horseradish, drained
  • 15ml Dijon mustard
  • 5ml Fresh lemon juice
  • 1 pinch Cayenne pepper

Instructions:

  1. Season the prime rib roast with 30g kosher salt, black pepper, and dried thyme 24 hours in advance. Before cooking, slather with 40g softened butter.
  2. Preheat oven to 250°F (120°C). Place roast on a rack in a roasting pan and cook until internal temperature reaches 120°F (49°C) for medium-rare.
  3. Remove roast from oven and let rest for 30 minutes. Use this time to prepare the sides.
  4. Boil the quartered Yukon Gold potatoes in heavily salted water until fork-tender. Drain and return to the hot pot for 2 minutes to steam off excess moisture.
  5. In a small saucepan, simmer 250ml heavy cream, 115g European butter, and 8 smashed garlic cloves over low heat for 10 minutes to infuse flavors.
  6. Pass the hot potatoes through a potato ricer or food mill. Gradually fold in the hot garlic-infused cream mixture, 10g sea salt, and 5g white pepper until velvety.
  7. Whisk together 240ml sour cream, 60g drained horseradish, 15ml Dijon mustard, 5ml lemon juice, and cayenne pepper in a small bowl. Serve alongside the sliced roast and potatoes.