
Pat dry the pork belly and use a sharp knife to score the skin lightly in a crosshatch pattern or prick it all over with a fork or something with a sharp tip.
Mix together the salt, pepper and five-spice powder, and rub the meat side with this mixture. Leave the skin dry and unseasoned.
Let the pork rest uncovered, skin side up in a cool place on the counter for about an hour or in the refrigerator overnight to dry the skin.
Preheat the oven to 390℉ (200℃).
Lightly brush the pork skin with a little of rice vinegar. Wrap the meat side tightly with foil, leaving only the skin exposed. Spread a layer of coarse salt (about ⅓–½ cup) evenly over the skin.
Place the wrapped pork on a wired rack over a baking sheet and then roast in the oven for 1 hour.
After roasting for an hour, take the pork belly out of the oven and carefully remove the salt crust.
Increase the heat to 410℉ (210℃) and return the pork (still wrapped in the foil) to the oven. Roast for another 30 minutes or until the skin is golden and blistered and the meat is tender.
Combine all ingredients for the dressing and adjust sweetness or acidity to taste.
Prepare the fine rice vermicelli sheets according to package instructions.
In a small saucepan, heat the oil over medium heat. Once the oil is hot, add the chopped scallions and stir briefly. Remove from the heat and transfer to a bowl.
Remove the pork from the oven and let it rest for about 10 minutes before handling. Then chop into bite-sized pieces.
On a large platter, layer the bánh hỏi sheets and drizzle scallion oil and sprinkle roasted peanuts. Top with pieces of pork belly.
Serve with lettuce, fresh herbs and dressing on the side.