Leave ham's plastic or foil covering intact and place ham in a large container (or a clean sink that plugs up well) and cover with hot tap water. Let rest 45 minutes.
Drain water then cover with hot tap water again and let rest 45 minutes longer. Near the end adjust oven rack to lowest position and preheat oven to 250 degrees.
Unwrap ham and remove plastic disk below ham bone. Place ham in oven bag and wrap bag so it fits snugly around ham. Tie bag and cut away excess plastic on top. Cut 4 small slits in top of bag.
Set ham cut-side down in a large roasting pan and bake in preheated oven until center registers 100 degrees on an instant read thermometer, about 1 - 1 1/2 hours (about 10 minutes per pound).
Near the end of baking, melt butter in a small saucepan over medium heat. Add in brown sugar, honey, mustard, pepper, cinnamon, ginger and cloves and cook, whisking constantly, just until sugar dissolves, about 2 - 3 minutes. Stir in orange zest and let cool just until it's about the consistency of honey, about 10 minutes (when ready to glaze ham rewarm glaze as needed if it has thickened too much).
Remove ham from oven. Increase oven temperature to 375 degrees. Cut oven bag and roll down to expose ham. Brush all over with 1/2 of the glaze. Bake in oven 5 minutes then remove and brush with remaining glaze. Bake 10 minutes longer. Remove from oven, tent with foil and let rest 10 minutes before carving and serving.
Recipe source: cooking method adapted from Cooks Illustrated
*Buy a ham that doesn't have water added.