Cut the the lean pork into thin slices; set aside the pork belly. Add the marinades and let it sit for at least 30 minutes
Preheat your wok until reall hot, add about 1/2 Tbsp of oil and add in the pepper and stir-fry until really fragrant, about 3 minute or so. Remove from the wok and set aside
Reheat the wok over a hot flame until smoke rises, then add 2 Tbsp of the oil and swirl to make sure the oil is evenly spread. Add in the sausage slices and stir-fry for about 10 seconds, Add in garlic and black bean and stir-fry for about 8 seconds, add in the pork slices and stir-fry until the pork is cooked through. Add the bell peppers back into the wok and stir-fry for about 1 minute
Give the corn-starch mixture a stir and pour into the work. Stir everything and the sauce will thicken almost immediately. Turn off the heat and serve immediately with rice as part of multi-course meal