Coating: Combine all of the ingredients in a bowl and set aside.
Season the lamb all over with salt and pepper, to taste. Heat the oil in an oven-safe skillet over medium-high heat. When the oil begins to swirl, add the lamb and sear it on all sides until golden and a nice crust has formed, about 2 minutes per side. Remove the lamb from the pan and brush with mustard on all sides. Press the coating onto the lamb, making sure to cover all sides. Put the lamb, bone side down, back in the pan and put it in the oven. Roast until the internal temperature reaches 125 degrees F on an instant-read thermometer, and the coating is golden brown, anywhere from 15 to 20 minutes for medium-rare. Remove the lamb from the oven and let it rest 5 minutes before serving.