To begin, prepare the pork and broth. In a medium pot, combine the water, soy sauce, fish sauce, sugar, five-spice powder, minced garlic, and quartered onion. Place the pork belly into the pot and bring it to a boil over medium heat. Skim off any impurities that rise to the surface, then reduce the heat to low. Cover and simmer for 45 minutes to 1 hour until the pork is tender.

Remove the pork belly from the pot and let it rest for a few minutes. Slice the pork thinly and set aside. Reserve the broth, as this will be used to flavour the noodles and serve as a light soup.

Prepare the Cao Lầu noodles according to the package instructions. If unavailable, thick rice noodles can be used as a substitute. Boil the noodles until just tender, then rinse under cold water to remove excess starch. Drain and set aside.

Heat a skillet over medium heat and add 1 tablespoon of oil. Sear the sliced pork belly until golden and slightly crispy on the edges. Set the pork aside and keep it warm.

Blanch the bean sprouts in boiling water for 30 seconds, then drain and set aside. Arrange the fresh lettuce and herbs on a serving platter for easy assembly.

In a small saucepan, warm the reserved pork broth. Adjust the seasoning with additional fish sauce or soy sauce if needed for a balanced savoury flavour.

Assemble the dish: Divide the noodles evenly among four bowls. Top each serving with seared pork slices, blanched bean sprouts, shredded lettuce, and a generous handful of fresh herbs. Sprinkle crushed peanuts and crispy pork skin (or fried wonton crisps) over the top.

Ladle a small amount of the warm broth into each bowl for added flavour. Serve immediately with lime wedges on the side for squeezing over the noodles and optional chili sauce or fresh chili slices for heat. Enjoy the delicate balance of savoury pork, fresh herbs, and chewy noodles that define this iconic dish from Hoi An.