01 -
Pat the prime rib very dry. Season all over with kosher salt and refrigerate uncovered on a rack set in a pan for 8-24 hours.
02 -
Take the roast out of the refrigerator 2 hours before cooking. Heat the oven to 225°F and place a rack in the lower third.
03 -
Mix olive oil, garlic, black pepper, rosemary, and thyme. Rub it over the top and sides of the roast, keeping most of it on the fat cap.
04 -
Set the roast bone-side down on a rack in a roasting pan. Roast until the thickest center reaches 118-120°F for medium-rare style slices, about 2 1/2 to 3 1/2 hours. For a USDA 145°F finished roast, cook longer and pull around 135-140°F.
05 -
Transfer the roast to a cutting board and tent loosely with foil. Rest for 45-60 minutes while the internal temperature rises and the juices settle.
06 -
Stir together sour cream, horseradish, chives, lemon juice, and salt. Refrigerate until ready to serve.
07 -
Increase the oven to 500°F. Return the roast to the oven for 8-12 minutes until the crust is deeply browned. Rest 10 minutes, cut away the bones, and slice across the grain.