Bring a medium wok of water to a boil, and blanch the pork belly for 2 minutes. Drain and set aside.
Heat vegetable oil in a wok, add onion and fry until it becomes golden. Transfer it to the cutting board and chop it.
Heat a wok until hot, add the pork belly and stir-fry until it shrinks.
Pour light soy sauce, dark soy sauce, and cooking wine in the wok. Stir-fry them a few times. Add ginger, shallots, garlic, anise, rock sugar, shiitake mushrooms, and the fried onions and stir fry for a few minutes.
Add in hot water just enough cover the pork and place the hardboiled egg, stew them for 1.5 hours under low heat.
Season with salt. Serve it with green vegetables and rice.