In a Ziploc bag, place all ingredients for char siu and close tightly. Massage to evenly coat pork belly with marinade. Place in a bowl or on a plate and marinate in the refrigerator for at least 2 hours to overnight.
Preheat oven 425°F.
Line a large baking dish with aluminum foil (I recommend a 4-quart roaster, about 3 inches deep). Pour everything from the Ziploc bag into the foil-lined baking dish. Turn pork pieces fat side up and spread ginger, green onion and garlic pieces around.
Roast uncovered in preheated oven for 1 hour, or until pork belly is fully cooked and tender.
Remove from oven and let rest for 15-20 minutes in baking dish before slicing. Meanwhile, get your rice in a serving bowl and chop the chives.
Slice char siu thinly and place top of rice. Sprinkle with chopped chives and enjoy!