Preheat your oven to 325°F (160°C).

In a large mixing bowl, whisk together the soy sauce, honey, sesame oil, minced garlic, grated ginger, rice vinegar, and red chili flakes, if using.

Add the pork belly pieces to the bowl, ensuring they are fully coated in the marinade. Let them soak for about 15 minutes.

Transfer the marinated pork belly to a baking dish or oven-safe skillet, spreading the pieces in a single layer.

Bake for about 1.5 hours, until the meat is tender and falls apart easily.

After baking, sprinkle sesame seeds over the top and turn on the broiler. Return the dish to the oven for an additional 5-10 minutes, watching closely to prevent burning.

Remove from the oven and let it rest for a few minutes before garnishing with fresh green onions.