Remove the bone (if any) from the Ham. Mix together the Mustard and Vinegar. Spread the mixture thinly on the Ham. Slice the Apples very thinly and place 2 layers on the Ham. Then sprinkle well with the Brown Sugar. Roll up the Ham the long way and hold together with skewers or tie with clean string. Place in a baking pan and dot with Butter. Bake in a moderate oven (350-375F) for 25 to 30 minutes. Baste several times while baking. Can be served whole or sliced.