Marinate chicken pieces for 20 minutes in marinade ingredients: soy sauce, Shaoxing wine, sesame oil and cornstarch. In a separate small bowl mix sauce ingredients: 3 tablespoons light soy sauce, Pixian doubanjiang, dark soy sauce and Shaoxing wine.
Heat wok over medium flame and add 3 tablespoons oil. Add garlic, ginger, scallion whites, dried chilies, Sichuan peppercorns, cumin, star anise and cassia and stir around until mixture becomes fragrant, for about 2 minutes, making sure that it doesn’t burn.
Turn heat up to high and add marinated chicken. Stir-fry until chicken is partially cooked and starting to take on some color, making sure not to burn the spices.
Make a well in the center of the wok, add the sauce mixture and cook briefly. Add 2 cups water, mix well and bring to a boil. Reduce heat to medium-low, cover wok and simmer for 10 minutes.
Add potatoes to the wok and return to a boil. Lower heat, cover wok and simmer 5 minutes if you like your potatoes slightly crisp, or up to 10 minutes for softer potatoes. Taste, and add salt if needed. Add bell peppers, cover wok and simmer an additional 3-4 minutes.
Meanwhile, bring a large pot of water to boil and cook noodles according to package directions, aiming to have them done just as the stew is done.Alternatively, cook noodles in advance until al dente, remove them with a spider or tongs to a colander and rinse under cool water to stop the cooking process. Retain the noodle water in the pot. Just before you are ready to serve the dish, bring the noodle water to boil and return the noodles to the pot to reheat them for a minute or so. Transfer hot noodles to a large wide plate or bowl and cover with the chicken stew. Garnish with scallion greens or cilantro and serve immediately.