PRIME RIB COOK TIME PER LB RECIPES

Steps:

• Mix up 1 tablespoon + 1 teaspoon each of onion salt, seasoned salt, and garlic powder, for a total of 1/4 cup of seasoning mix.
• Pat the seasoning mix on both ends of the roast as well as the fat side. (The salt may not stick as well on the fat side, but don’t worry about it.)
• Set the seasoned roast on a roasting rack, bone-side down and fat-side up. Place the rack in a large roasting pan, and insert your meat thermometer into the middle of the roast.
• Place the roast into a 500° preheated oven, uncovered, and cook for 5-6 minutes per pound.
• Then shut the oven off completely, and DO NOT OPEN THE OVEN DOOR FOR TWO HOURS. 
• After two hours, check the temperature of the meat. If your thermometer reads 135-140°F, it’s done! (If it isn't quite to temp yet, just put it back in the oven at 375°F until it's done.)
• Creamy Horseradish Sauce

Steps:

• 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.
• 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.
• Meanwhile, whisk sour cream, horseradish, pepper, salt, and 1/4 cup mustard in a small bowl; set aside.
• 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.
• Sour cream sauce can be made 1 day ahead. Transfer to an airtight container and chill.