1. Place ham, fat side up, on a rack in a shallow roasting pan. Insert meat thermometer into the thickest part of meat without touching bone.
2. Bake in slow oven (325°) 2 1/4 hours; remove from oven; cut away the rind and score the fat.
3. Mix corn syrup, brown sugar and mustard in a small bowl; brush part over ham.
4. Continue baking, brushing several times with glaze, 30 minutes, or until richly glazed and thermometer registers 140°.
5. Remove to a heated serving platter. Let stand 20 minutes before slicing.