In a large pot, combine pork belly, garlic, shallots, bay leaves, peppercorn, pork cubes (if using), and salt. Add enough water to cover the pork belly.
Bring the water to a boil over medium-high heat, then reduce the heat to a simmer. Cook until the pork is fork-tender, typically around 60 minutes, depending on the size.
Remove the pork from the pot and allow it to drain. For optimal crispiness, air-dry the pork for at least 30 minutes or until the skin is no longer moist.