1/2 lb skinless pork belly, cut into 2-inch chunks
1/2 lb boneless pork shoulder, cut into 2-inch chunks
Kosher salt and freshly ground black pepper
White sugarcane vinegar
3 tablespoons vegetable oil
1 medium red onion, diced
2 tablespoons minced fresh ginger
2 tablespoons minced garlic
1 cup chicken stock
2 long red chiles
1/2 cup pork blood
In a large bowl, toss the pork belly and shoulder with salt and pepper and enough vinegar to lightly coat the meat. Cover and marinate in the refrigerator for at least 1 hour or overnight.
Remove the pork chunks with a slotted spoon and set them aside.
In a Dutch oven, heat the vegetable oil over medium heat. Add the onion, ginger, and garlic and cook, stirring occasionally, until the garlic is just beginning to brown and the onion is soft and translucent, about 4 minutes.
Add the pork chunks to the pot and cook, stirring occasionally, until they just begin to brown, 5-7 minutes. Be careful not to let the onion, ginger, and garlic burn.
Add the stock, 1/2 cup of vinegar, the chiles, and water as needed to fully cover the pork. Bring the liquid to a boil, then reduce the heat until it is cooking at a low simmer. Cover the pot and cook until the meat is fork-tender. This should take 35-40 minutes, but check it after 20 minutes.
When the pork is tender, stir in the blood and let it just cook through - it will thicken and darken in color - 3-5 minutes. Taste and add fish sauce and vinegar to your liking.
Ladle into bowls and serve with puto or white rice.