DRY THE HAM THOROUGHLY with paper towels. Cut the scallions into 8 cm segments. Choose a heavy casserole or pot, large enough to hold the ham comfortably. Heat the pot and then add the oil, ginger, garlic and scallions, and stir-fry in the pot for 2 minutes. Push the aromatics to the side and brown the ham on each side until it has some color, 10 to 15 minutes. Pour off the oil. Add all the braising liquid ingredients to the pot and bring the mixture to a boil. Turn the heat down to a simmer, cover tightly and cook for about 4.5 hours, turning the ham from time to time. When the ham is tender, remove it gently with a large spatula. The meat should be literally falling apart. Place it on a serving platter. Strain the sauce, skim off any surface fat, and reduce the liquid until it is slightly thick. Pour this over the ham and serve.