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 per 500g for a rare roast or 40-50 minutes per 500g 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.
Serve with a jus or brown gravy, roast parsnips, blanched baby beetroot and green beans.
Gravy:
Drain excess fat from the roasting tin. Put the roasting tin directly over a low heat, sprinkle in the flour and mix into a thick paste.
Slowly add 1 cup of stock, stir continuously to avoid any lumps, the gravy will thicken as it comes back up to the boil. Season to taste and strain the mixture into a jug.