In a mixing bowl, combine the spring onions, garlic chives, shallots, garlic, black pepper, fish sauce and soy sauce.
In separate bowl, combine half the marinade, minced pork, and egg and mix well.
Add the sliced pork belly to the remaining marinade. Cover and marinate both meats in the refrigerator for 2 hours, or overnight for a better result.
Form the pork mixture into small round balls with oiled hands, then slightly press down on each ball to form patties, about 2 inches/5 cm in diameter and 1/2-inch/ 1 cm thick.
Heat a charcoal grill or barbecue to medium-high and grill the patties for 4 minutes on each side. Grill the pork belly for 2 minutes on each side or until brown.
Place the noodles, herbs and patties on three separate platters.
Transfer to 4 to 6 dipping bowls.
For the dipping sauce: Add fish sauce, vinegar, sugar and water to a saucepan. Mix, then bring to the boil. Transfer to a dipping bowl and add chile, garlic and lime juice.
Each guest should have their own dipping bowl, with all the ingredients in the middle of the table. Take a mixture of noodles, herbs and meat and dip into the warm fish sauce with every mouthful.