Score ham about half-inch deep with a sharp knife. Place ham on a rack in a shallow baking pan. Bake at 325 degrees for 2 to 2-1/2 hours ( 20 minutes per lb). Combine brown sugar, mustard and enough vinegar to make a thick paste. During the last hour of baking, brush glaze on ham every 15 minutes. Yield: 10-14 servings.
Recipe by Amish 365 at https://www.amish365.com/amish-ham-glaze/