Remove roast from fridge and let come to room temperature, 20 min. Preheat oven to 325°F (160°C). Rub mustard all over beef and then rub with thyme, rosemary, salt and pepper. Place beef in a shallow roasting pan and roast about 1 1/2 hours for medium-rare or until a meat thermometer registers 145°F (63°C) when inserted into the thickest part of the roast, away from the bone.
Once the roast is cooked, transfer beef to a cutting board and let rest for 15 min. Transfer it to platter and cut beef across the grain into thin slices. Serve with Dijon-Thyme Sauce.