I made this for Christmas dinner and it turned out amazing. There was so much au-jus that I was able to make gravy with some of it. The vegetables were so flavorful by roasting them with the meat. Delicious.
Take the prime rib and rub salt over entire outside and leave covered in the refrigerator for 48 hours before roasting.
Remove Prime rib from refrigerator and remove bone from bottom of rib. Reserve the bone. Mix the butter, garlic, herbs,mustard, and worcestershire, salt and pepper in a food processor until well blended. Spread on outside of prime rib. Let sit on counter for 1 hour before roasting.
Meanwhile trim vegetables and spread out in bottom of roasting pan. Add the beef stock, ox tails, bone from prime rib, wine, garlic and tied herbs to stock.
Preheat oven to 325 degrees. Place prime rib on rack in center of roaster. Roast uncovered until internal temp reaches 115 for medium rare. Remove from oven.
Add oil to hot skillet and sear the prime rib on all sides about 3 minutes per side. Set on carving board tented with foil and let rest 20 to 30 minutes.
Mix all ingredients for horseradish sauce together and refrigerate until ready to serve.
Remove bones, garlic, tied herbs,onions and ox tails from roaster and discard. With slotted spoon remove cooked carrots and brussels sprouts for serving.
strain the au-jus through fine mesh strainer and discard solids.
Carve the rested prime rib and serve with au-jus and horseradish cream