Set sous vide to 180F (82C)
In a saucepan, bring cooking wine to a boil on medium high. Turn down the heat, add in soy sauce, dark soy sauce, rock sugar, ginger, and water. Bring back to a boil until rock sugar is dissolved. Set aside to cool.
Cut Pork belly into 2”x2” cubes.
Cut a length of butchers twine long enough to wrap the pork like a gift.
Place twine on the cutting board, place the pork on the twine meat side down.
Criss-cross on the top and tie it back on the meat side.
Place pork belly in a vacuum seal bag with the skin side facing the smooth surface of the bag.
Place the scallion on the meat side, and pour in the marinade.
Seal the bag using the pulse function of a vacuum sealer or use the water displacement method and hang the opening off the side of the tub.
Sous vide for 16 hours.
Once time is up, remove the bag from the water bath.
Carefully pour the liquid into a fat separator, pour only the marinade (leaving the fat) through a strainer into a wok or pot.
Bring the sauce to a boil, then turn it down to a simmer.
Give the sauce a taste and adjust it to your desired sweetness by adding sugar. If it’s too salty add water to taste. When you reach desired taste, add the cornstarch slurry and mix into the marinade. Allow it to thicken so that it can coat the back of a spoon.
To serve, place pork onto a bed of bok choy, and pour sauce over each piece of pork so that it sticks and glistens. Serve with a large bowl of rice.