Place an unwrapped boneless prime rib on a baking sheet. Generously salt all over and refrigerate overnight to air-dry the outside of the prime rib.
10-15 lbs boneless prime rib, 1 tablespoon coarse kosher salt
Bring the prime rib to room temperature before roasting. It usually takes about 2 hours out on the counter.
In medium bowl, mix together butter, garlic, thyme, rosemary, black pepper and garlic powder. Smear the mixture over the top (fat side) and sides of the roast. Transfer the roast onto a roasting pan, buttered side up. (I use this roasting pan, and highly recommend it.) 2 sticks (225g) unsalted butter, 1 tablespoon freshly grated garlic, 1 teaspoon dried thyme, 1 teaspoon dried rosemary, 1 teaspoon ground black pepper, 1 teaspoon garlic powder
If roasting garlic, slice the top off, drizzle some olive oil and sprinkle some salt. And then wrap in a foil. (Here's my detailed roasted garlic recipe.) A few garlic heads
Preheat the oven to 200°F (95°C).
Roast the meat in the oven until the center of the roast reads 120-125°F (50°C) on a meat thermometer for medium-rare, or 130°F (55°C) for medium doneness, about 5-5.5 hours. (This Thermapn Mk4 meat thermometer is my favorite! Super quick and reliable! (<- affiliate link) Remove the prime rib from the oven, cover with a foil and rest for about 30 minutes.
Meanwhile, increase the oven temperature to 500°F (260°C).
Once the oven reaches 500°F, put the prime rib into the oven, uncovered, and cook it until it’s nice and brown, and crisp on the outside, about 10 minutes. Rest the roast for at least 15 minutes before slicing.