Lynne Curry's Prime Rib with Mustard and Herb Butter

Directions

1. Melt the butter in an 8-inch skillet over medium heat. Let it foam until it turns light brown and smells nutty, about 5 minutes. Immediately pour the butter into a small heatproof bowl, leaving most of the milk solids in the bottom of the skillet. Refrigerate the butter until solid, about 1 hour (or freeze, to speed this up).
2. Purée the garlic, rosemary, sage, thyme, mustard, Worcestershire, 1 1/2 teaspoons salt, and 1 teaspoon pepper with the solidified browned butter in a food processor to make a thick paste. Reserve 1/4 cup of the butter and rub the rest all over the roast. Put the roast fat side-up on a rack set in a roasting pan and let sit at room temperature for 1 hour before roasting.
3. Position a rack in the center of the oven and heat the oven to 300° F. Roast the beef until an instant-read thermometer registers 110° F for rare, about 1 1/2 hours, or 115° F for medium rare, about 10 minutes more. Remove the roast from the oven. Let sit, tented loosely with foil, for up to 2 hours (or continue with the recipe).
4. To sear in the oven: Heat the oven to 475° F. Roast until 125° F for rare or 130° F for medium rare, about 10 minutes.
5. Or, to sear on the stove: Heat the oil in a heavy 12-inch skillet until shimmering hot. Sear the beef, turning and pressing down with tongs, until browned all over and cooked to desired temperature, about 4 minutes per side. Transfer to a cutting board. If there was no earlier rest between roasting and searing, let the roast rest for 15 to 20 minutes. Slice and serve with the reserved mustard butter.
6. The beef can be roasted and then sit at room temperature, tented with foil, for up to 2 hours before the final sear.