Place ham in a large container; cover with cold water. Soak for 16 hours in the refrigerator; change water once. Pour off water. Scrub ham in warm water with a stiff brush; rinse well. Cut skin from ham; trim off fat. Insert cloves in ham.
Preheat oven to 325 degree F. Place ham, fat-trimmed side up, in a large roasting pan. Insert a meat thermometer into the thickest portion of the ham, making sure it doesnt touch fat or bone. Pour apple cider or apple juice over ham.
Bake ham, covered, in the preheated oven for 4 to 4-1/2 hours or until the meat thermometer registers 160 degree F. Drain off the pan juices.
For glaze, combine brown sugar and ground cloves. Add just enough sherry or wine vinegar to make a paste. Spread glaze over fat side of ham.
Bake ham, uncovered, about 30 minutes more or until the meat thermometer registers 170 degree F. Let stand for 15 to 20 minutes before slicing. Transfer to a large platter and, if desired, garnish with pears and lemon leaves. Makes 25 to 30 servings.