Brine the Roast: Generously coat the prime rib roast with kosher salt, wrap in plastic, and refrigerate for at least 24 hours.

Prepare Room Temp: Remove the brined roast and let it sit at room temperature for 5-6 hours.

Preheat Oven: Preheat your oven to 250°F (120°C).

Prepare the Au Jus: In a large pot, heat olive oil and brown meaty bones, then add garlic, carrots, celery, and onion.

Simmer the Au Jus: After deglazing with red wine, add beef stock, thyme, and bay leaf. Simmer gently.

Cook the Roast: Cook the roast in the oven until the internal temperature reaches 115°F for rare or 120°F for medium-rare, about 3 hours.

Rest the Roast: Remove from oven, tent with foil, and let rest for 20-30 minutes.

Brown the Crust: Broil the roast for 1–2 minutes on each side until the crust is golden.

Prepare the Horseradish Sauce: Mix all sauce ingredients until smooth.

Serve: Slice against the grain, drizzle with au jus, and serve with horseradish sauce.