Boil noodles per package, drain, rinse with cold water, and set aside.
Toss sliced chicken with soy sauce and cornstarch. Let sit while prepping.
Whisk soy sauce, oyster sauce, hoisin, sesame oil, sugar, garlic, ginger, and broth.
Sear chicken in oil over medium-high heat until browned and cooked. Set aside.
Add more oil, stir-fry bell pepper, carrots, and snap peas until just tender.
Return chicken, add noodles and sauce. Toss until coated and heated through.
Top with green onions. Add sesame seeds or chili flakes if desired.