Place ham, straight from the refrigerator, on a rack in a shallow roasting
pan. Add 1/2 cup water. Insert an ovenproof meat thermometer into the thickest
part of the ham. Cover the pan tightly with aluminum foil, leaving the thermometer
Roast at 325 degrees F until thermometer registers 135 degrees F, about
19-23 minutes per pound.
Meanwhile, combine rhubarb, sugar, orange juice, orange peel, dry mustard
and cinnamon stick in a large saucepan. Bring to a boil. Reduce heat to medium
and cook, uncovered, about 15 minutes, stirring occasionally.
Remove cinnamon stick. Remove aluminum foil from ham and spoon a small amount
of sauce over the ham 15 minutes before end of cooking time. Remove ham when
meat thermometer registers 135 degrees F.
Allow ham to stand, covered, about 10 minutes, or until the thermometer
registers 140 degrees F.