Combine parsley, lemon zest, lemon juice, thyme, juniper berries, garlic, pepper and chile powder in a blender or food processor. Start drizzling in oil, blending until smooth.
Rub mixture over surface of the roast. Cover and refrigerate for at least 24 hours.
Bring roast to room temperature before proceeding. Place roast in large heavy roasting pan with a raised grate, and roast in preheated oven at 500 degrees for 15 minutes. Reduce temperature to 350 degrees Place a digital read probe meat thermometer in the center of the roast and cook until temperature reaches 135 degrees for medium rare. Remove from oven and tent with foil. Let roast rest for 15 minutes before carving.
Notes
Prime Rib Internal Temperature Guide:A bone in prime rib roast is traditionally served rare to medium rare. If you want to cook it to a more "done" state, here is an internal temperature guide.
Rare: 125 – 130 degrees
Medium Rare: 130 – 140
Medium: 140 – 150
Medium Well: 150 – 160
Well: Over 160 degrees
Tips For Success:
Don't skip the steps for letting the prime rib roast come to room temperature before cooking. The roast will cook more evenly.
Don't skip letting the meat rest before slicing. This rest time allows the juices to redistribute in the meat. If you slice too soon, all of that glorious flavor will run out on the cutting board.