Method. Preheat oven to 200oC. Wipe roast with damp paper towels. Combine flour, mustard, salt and pepper in a small bowl and rub all over beef. Place the roast, fat side up in a roasting pan and roast, uncovered, for 30-40 minutes for a rare roast or 40-50 minutes for a medium roast.Once cooked, cover with foil and let stand for 15-20 minutes for easier carving. Reserve the cooking juices to make a gravy or jus, if desired.ombine flour, mustard, salt and pepper in a small bowl and rub all over beef. Place the roast, fat side up in a roasting pan and roast, uncovered, for 30-40 minutes for a rare roast or 40-50 minutes for a medium roast. Once cooked, cover with foil and let stand for 15-20 minutes for easier carving.