Mustard-Crusted Boneless Prime Rib Roast with Cream Sauce

Name: Mustard-Crusted Boneless Prime Rib Roast with Cream Sauce
Total time: 5 h 20 min
Yield: 8 servings
Ingredients: 1 piece boneless prime rib roast; 4 tablespoons Montreal-style steak seasoning; 1 cup sour cream; ¼ cup prepared horseradish; 1 teaspoon freshly ground black pepper; ½ teaspoon kosher salt; ½ cup Dijon mustard; ¼ cup unsalted butter

A luxurious prime rib roast encrusted with mustard and Montreal steak seasoning, slow-roasted to perfection and served with a creamy horseradish sauce. This impressive main dish is perfect for special occasions.

8 servings

5 hr 20 min

Published October 4, 2025

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Ingredients

•1 piece boneless prime rib roast
•4 tablespoons Montreal-style steak seasoning
•1 cup sour cream
•¼ cup prepared horseradish
•1 teaspoon freshly ground black pepper
•½ teaspoon kosher salt
•½ cup Dijon mustard
•¼ cup unsalted butter

Cooking Instructions

1.
Season roast all over with 2 Tbsp. steak seasoning. Transfer to a wire rack set inside a rimmed baking sheet and let sit at room temperature 1 hour.
60 min
2.
Preheat oven to 225°F. Roast beef until an instant-read thermometer inserted into the center registers 120°F, 3 1/2-4 hours (start checking every 5-10 minutes after 3 1/2 hours). Tent with foil and let sit at least 30 minutes and up to 1 hour. Increase oven temperature to 500°F.
240 min
3.
Meanwhile, whisk sour cream, horseradish, pepper, salt, and 1/4 cup mustard in a small bowl; set aside.
5 min
4.
Remove string from roast; discard. Stir butter and remaining 1/4 cup mustard in another small bowl. Using a pastry brush, thickly coat roast with mustard-butter sauce. Coat with remaining 2 Tbsp. steak seasoning. Roast beef until a brown crust forms, 5-10 minutes. Transfer to a cutting board and carve. Serve with sour cream sauce alongside.
10 min
5.
Sour cream sauce can be made 1 day ahead. Transfer to an airtight container and chill.
5 min

Cooking Instructions

Season roast all over with 2 Tbsp. steak seasoning. Transfer to a wire rack set inside a rimmed baking sheet and let sit at room temperature 1 hour.

60 min

Preheat oven to 225°F. Roast beef until an instant-read thermometer inserted into the center registers 120°F, 3 1/2-4 hours (start checking every 5-10 minutes after 3 1/2 hours). Tent with foil and let sit at least 30 minutes and up to 1 hour. Increase oven temperature to 500°F.

240 min

Meanwhile, whisk sour cream, horseradish, pepper, salt, and 1/4 cup mustard in a small bowl; set aside.

5 min

Remove string from roast; discard. Stir butter and remaining 1/4 cup mustard in another small bowl. Using a pastry brush, thickly coat roast with mustard-butter sauce. Coat with remaining 2 Tbsp. steak seasoning. Roast beef until a brown crust forms, 5-10 minutes. Transfer to a cutting board and carve. Serve with sour cream sauce alongside.

10 min

Sour cream sauce can be made 1 day ahead. Transfer to an airtight container and chill.

5 min