1. 
The Dry Brine: At least 24 hours before cooking, rub the roast generously with kosher salt and leave it uncovered in the fridge on a wire rack. 
2. 
Prep: Remove the roast from the fridge 2 hours before cooking to bring it to room temperature. Preheat oven to 225°F (107°C).
3. 
The Rub: Mix the butter with rosemary, garlic, and black pepper. Slather the mixture over the entire roast.
4. 
Low & Slow: Place the roast in a roasting pan (bone side down) and bake until the internal temperature reaches 120°F (49°C) for medium-rare—this may take 3 to 4 hours.
5. 
The Rest: Remove from the oven, tent loosely with foil, and let it rest for at least 30 to 60 minutes.
6. 
The Sauce: While resting, whisk together all Horseradish Sauce ingredients and refrigerate.
7. 
The Jus: Collect 4 tbsp of drippings in a pan, deglaze with red wine over medium heat, then whisk in beef broth and simmer until reduced.
8. 
The Sear: Increase oven to 500°F (260°C) or use a hot cast iron skillet. Place the rested roast back in for 6–10 minutes until a dark, mahogany crust forms.
9. 
Serve: Carve into thick slices and serve immediately with the Jus and Horseradish Sauce
