To Cook Fry the drained preserved mustard greens and half of the ginger without water and oil in a pan or wok at low-medium heat, until the aromatic and dry. Put aside.Bring a pot of water to boil and add the pork belly, blanching for 5 mins. Dry the pork belly and fork small holes in the skin. Cover in the dark soya sauce. Put aside for 30 mins. Cook the pork belly in a pan heated up with 2 tbsp of oil. Brown all sides of the pork. Remove from the pan.Leave the pork for 10 mins and cut into 1cm slices. Heat up a pan or wok with 1 tbsp of oil. Fry the garlic and the rest of the ginger till it is aromatic.Add the preserved mustard greens to the pan. Stir-fry briefly. Add the star anise, soy sauce, oyster sauce and cooking wine. Simmer for 15-20 mins. Season according to taste. Place the pork belly skin side down on a bowl and layer the preserved mustard greens on top. Steam for 2 hours. Serve while hot with rice.