Wash the pork belly and vegetables. Then, drain and set them aside. Add a little salt to a pot of water, then blanch the pork for 30 seconds to 1 minute over medium heat.
Dispose of the water that you used to blanch the pork and fill the pot with new water. Add the leek, onion, ginger, and white wine to the pot. Boil the water for 5 minutes to infuse it with herbs and spices.
Put the pork in the pot and boil it for 30 minutes.
After cooking the pork, transfer it to an ice bath or cold water.
Add the Vietnamese scallion and oil garnish to a saucepan. Stir in some minced garlic and fry them until fragrant. Pour in the soy sauce, sugar, chili pepper, and vinegar. Stir well until the sauce boils, then cut the heat.
Place the boiled pork belly on a chopping board and cut it into thin slices. Arrange the pork pieces on a plate.
Serve the boiled pork with a plate of vegetables and herbs and a bowl of dipping sauce on the side.