Heat oven to 325°F. Place ham cut-side down in a roasting pan with water; cover tightly with foil.

Bake 90 minutes. Mix brown sugar, mustard, honey and vinegar.

Uncover ham; brush with half the glaze. Bake 20–30 minutes, brushing again halfway, until a commercially packaged cooked ham reaches 140°F; reheat repackaged ham to 165°F.

Rest 10 minutes before slicing.