Cook the noodles according to the package directions. Drain and toss with a touch of vegetable oil to prevent clumping. Set aside.
While the noodles cook, prepare the vegetables. Keep the white parts of the scallions separate from the green tops. Optional Add-ins: garlic, carrot, cabbage, celery, msg, oyster sauce
Heat the vegetable oil in a wok or large pan over medium heat. Add the onion, followed by the bell peppers and broccoli. Stir-fry for 2–3 minutes.
Add salt, mushrooms, and sesame oil. Continue cooking for another 2–3 minutes, stirring often.
Grate in the fresh ginger and add garlic if using. Stir in the chili crisp for a light heat and depth of flavor.
Add the leftover chicken and warm through for about 2 minutes.
Toss in the pre-cooked noodles, soy sauce, and hoisin sauce. Stir well to coat everything evenly. You may also add a teaspoon of oyster sauce or a splash of Chinese cooking wine at this point if desired.
Cook for 2–3 minutes, stirring until everything is heated through.
Turn off the heat, top with the green parts of the scallions, and give it all one final toss. Serve hot.