Rinse the pork under cold water and pat dry with paper towels.
Add the marinade ingredients to the pork. Mix well and let it rest for 15 minutes.
Heat a wok until hot. Add the lard and let it melt.
Add the black bean paste and stir constantly over medium heat for 3 to 5 minutes.
Add the brown sugar and stir for 2 to 3 minutes.
Remove the black bean paste (leave the fat in the wok) and set aside. Keep the oil in the wok for the next step, and keep the wok hot.
Add the pork to the wok and stir-fry until half cooked.
Add the onion, zucchini, and potato; stir-fry for 3 to 5 minutes, until about one-third cooked.
Add the mushrooms and cabbage; stir-fry for 2 to 3 minutes.
Stir the cooked black bean paste back into the wok and combine with the vegetables. Cook, stirring, for 1 to 2 minutes.
Add the chicken stock, water, and Shaoxing wine. Simmer over medium heat for 5 to 7 minutes. (Cover the wok with a lid, if possible, to speed up cooking.)
Meanwhile, bring a pot of water to a boil. Add the noodles and cook for 3 to 5 minutes.
Rinse the noodles under cold water and drain. Place them in a bowl.
Add the starch-and-water slurry to the wok, then stir. (This will thicken the sauce and is the final step in making the black bean sauce.)
Spoon the black bean sauce over the noodles. Serve as is or garnish with cucumber slices, green peas, sweet corn, or a hard-boiled egg.
Mix the sauce and noodles well with chopsticks.
Notes
Feel free to swap in udon noodles and adapt the recipe to your taste—the sauce is what matters most.