In a bowl, combine the fish sauce, sugar, garlic, and black pepper. Add the pork cubes and mix to coat evenly.
Heat the oil in a large skillet over medium-high heat. Add the pork and cook, stirring occasionally, until browned, about 5 minutes.
Add the soy sauce, rice vinegar, and water to the skillet. Bring to a boil, then reduce the heat to low. Simmer, stirring occasionally, until the pork is tender and the sauce is thickened, about 20 minutes.
Stir in the green onions and chili pepper (if using). Cook for 1 minute longer.
Serve over rice or noodles.
Interesting Facts
Caramelized Pork Belly Thit Kho is a traditional Vietnamese dish that is typically served with rice.
The pork belly is cooked until it is tender and juicy and the sauce has a subtle sweet and sour flavor.
The dish is a great way to use up leftover pork belly, as the flavors intensify with time.
It can be served as a main dish or as an appetizer.