For the Pork Belly:
Combine equal parts sugar and salt with black pepper and thyme to create a cure. Cover the pork belly with the cure and let sit overnight.
The next day, rinse off the cure. Place the belly in an appropriately sized pan and cover with water, soy, and sugar. Place in 325°F oven for 3 to 5 hours. When the belly is tender, remove from the oven and let rest in the braising liquid for 1 hour. When cool enough to handle, place in refrigerator and chill.
For the Scallion Pancakes:
Mix all-purpose and tempura flours in a large bowl and slowly start to whisk in the cold water until it's the consistency of pancake batter. Add the scallions and season to taste. Let the batter rest for 30 minutes.
To Assemble and Serve:
Cut the cooled belly into appropriate size pieces and reheat in oven at 350°F. If you prefer, once the belly is warm, crisp up, skin side down, in a Teflon pan.
For the pancakes, get a Teflon pan hot, add ¼ cup canola oil, and use a ladle to drop the batter into the pan. The ladle will naturally help form the batter into a circular shape. Cook until pancakes are golden brown and crisp on both sides.