Place the pork belly into a large bowl. Place the rice grains into a mortar and grind to a fine powder.Transfer to a bowl. Add the Chinese cooking wine, and mix well. Add this to the pork belly. Massage the liquid into the flesh. Set aside to marinate for at least 30 minutes.
Transfer the pork to a medium-sized pot and cover with cold water. Add the salt, sugar, ginger and black cardamoms. Bring to the boil, skimming any impurities from the surface.
Cover, reduce heat to low, and simmer for 3-4 hours or until tender.
Garnish with coriander.