Preheat an oven to 325°F. Place the pork belly in a pot and cover with cold water. Bring to a boil. Reduce the heat and simmer for 15 minutes. Make sure to skim the foam.
Remove the pork belly from the water and cut into 16 equal square pieces.
In a dutch oven, mix the sugar and water over medium-high heat. Whisk until the sugar has dissolved. Add the pork belly and coat.
Add the sake, soy sauce, chicken broth, ginger, cinnamon stick, star anise, bay leaves, chiles de arbol, and black peppercorns. Bring to a boil. Cover and transfer to the oven.
Bake for 30 minutes . Add the scallions. Cover again and bake for another 30 minutes.
Increase the heat of the oven to 375°F. Remove the cover and bake for 40 minutes. Stir the contents every 10-15 minutes to help brown all sides of the pork.
After the pork has cooked, take a cup of the sauce the pork cooked in and placing it in a saucepan. In a bowl, combine 2 tsp cornstarch with 1 tsp water. Add that to the saucepan and whisk until the sauce thickens.
Serve the pork on top of rice and drizzle with the thickened sauce.