In a large pot, bring water to a boil and add the sliced pork belly. Cook for about 15-20 minutes until the pork is tender. Drain and set aside.
Heat the vegetable oil in a wok or large skillet over medium heat. Add the minced ginger and garlic, and stir-fry for a minute until fragrant.
Add the chili bean paste to the wok and stir-fry for another minute. Then, add the cooked pork belly and continue stir-frying for a few minutes until the pork is slightly browned.
Pour in the soy sauce, Shaoxing wine, and sugar. Stir well to coat the pork evenly with the sauce.
Add the sliced bell peppers and leek to the wok and continue stir-frying for a few more minutes until the vegetables are tender-crisp.
Taste and adjust the seasoning with salt if needed.
Serve the Twice-cooked pork hot over steamed rice and enjoy!