Magnolia's Famous Prime Rib Recipe

Prepare the roast

Remove the prime rib from the refrigerator 2–3 hours before cooking to come to near room temperature. Pat the roast dry with paper towels.

Season

Combine kosher salt, black pepper, garlic powder, onion powder, chopped rosemary and thyme in a small bowl. Rub vegetable oil over the roast surface, then coat the roast evenly with the seasoning mixture, pressing to adhere. Ensure the fat cap and all surfaces are seasoned.

Roast low and slow

Preheat oven to 225°F (107°C). Place the roast bone-side down on a rack in a shallow roasting pan (bones act as a natural rack). Insert an oven-safe probe thermometer into the thickest part of the meat without touching bone. Roast until the internal temperature reaches 115°F for rare or 125°F for medium-rare (this will vary based on roast size; plan for approximately 20–30 minutes per pound at 225°F).

High-heat finish

Remove roast from oven when it hits the target low temp (115–125°F). Increase oven temperature to 500°F (260°C). Return the roast to the oven and roast 8–12 minutes, or until the exterior is deeply browned and the internal temperature reaches 125°F for rare or 135°F for medium-rare. Watch closely to avoid burning.

Rest and slice

Transfer roast to a cutting board and tent loosely with foil. Let rest 20–30 minutes; internal temperature will rise ~5–10°F. For service as 'ten ounce cut', trim and slice 10 oz portions against the grain to desired thickness. Reserve pan drippings for au jus.

While the roast rests, combine prepared horseradish, sour cream, mayonnaise, lemon juice, salt and pepper in a small bowl. Taste and adjust: add more horseradish for heat, more sour cream for creaminess, or a little more lemon for brightness. Chill until serving.

Pour pan drippings into a fat separator or a heatproof measuring cup. Spoon off excess fat until about 1–2 tablespoons of fat remain with the drippings (reserve excess fat for another use). Place roasting pan over two burners on medium heat (or transfer drippings to a saucepan).

Add red wine to the pan and scrape the browned bits (fond) from the pan with a wooden spoon, reducing for 1–2 minutes until slightly concentrated. Add beef stock and Worcestershire sauce and bring to a gentle simmer for 3–5 minutes to meld flavors.

To thicken slightly: whisk the teaspoon of flour into a small amount of cold water to make a slurry (or mix cornstarch with cold water). Whisk the slurry into the simmering liquid and cook 1–2 minutes until slightly thickened. Season with salt and pepper to taste. Strain the au jus through a fine-mesh sieve into a warm serving vessel.

Serve warm alongside sliced prime rib with a dollop of horseradish cream and a small bowl of au jus for dipping.