Step 1: At least 2-3 hours before roasting, remove the prime rib from the refrigerator and pat it thoroughly dry with paper towels. Allow it to come to room temperature.
Step 2: If not already done, carefully score the fat cap of the prime rib in a crosshatch pattern, being careful not to cut into the meat. This helps the fat render during cooking.
Step 3: In a small bowl, combine the kosher salt, freshly ground black pepper, garlic powder, finely chopped fresh rosemary, and fresh thyme. Mix well to create the herb rub.
Step 4: Generously rub the herb mixture all over the prime rib, pressing it firmly into the fat cap and all sides of the meat. Place the seasoned roast on a rack set inside a large roasting pan.
Step 5: Preheat your oven to 250°F (120°C).
Step 6: Insert an oven-safe meat thermometer into the thickest part of the prime rib, avoiding the bone. Place the roasting pan with the prime rib in the preheated oven.
Step 7: Roast for approximately 2-3 hours, or until the internal temperature reaches 120-125°F (49-52°C) for medium-rare. Adjust for your desired doneness (115-120°F for rare, 125-130°F for medium).
Step 8: Once the desired internal temperature is reached, remove the prime rib from the oven and transfer it to a cutting board. Tent loosely with foil. Increase the oven temperature to 450°F (232°C).
Step 9: Once the oven is fully preheated, return the prime rib to the roasting pan. Roast for an additional 10-15 minutes, or until a beautiful, deep brown crust forms. Watch closely to prevent burning.
Step 10: Remove the prime rib from the oven and transfer it back to the cutting board. Tent it loosely with foil and let it rest for at least 20-30 minutes. This is crucial for juicy results.
Step 11: Carve the prime rib by carefully separating the meat from the bones, then slice against the grain into desired thickness. Serve immediately with your favorite sides and au jus.