Bring the prime rib to almost room temperature (about 1 hours)
Once the prime rib is come to room temperature, place in an oven proof dish or case iron skillet(I use CI skillet) paint heavily with creamy horseradish sauce. Coat the entire roast with Montreal steak seasoning. Place the rosemary sprigs on top. Cover with paper towel and let sit for an additional hour.
Preheat oven to 500. (I know this temperature seems high but trust me its perfect)
Next and most importantly, you will need to cook your prime rib, uncovered and at 500 for five minutes per pound. So for example, if your roast is 5 pounds you will need to cook it at 500 for 25 minutes.
Next, once you have reached your desired cook time you will need to turn your oven off and do not, I repeat DO NOT open the oven door for 2 hours! Your prime rib will be perfectly medium to medium rare. This method works both with boneless and bone in Ive used both, perfect every single time enjoy!
