Marinate the chicken with soy sauce, sesame oil, and cornstarch for 10 minutes.
Cook noodles according to package, drain, and toss with sesame oil.
Whisk together soy sauce, rice vinegar, hoisin, honey, sesame oil, water, ginger, garlic, and sesame seeds to make the sauce.
Cook marinated chicken in olive oil until browned, then set aside.
Stir-fry vegetables, add green onions, then combine with chicken and sauce. Toss with noodles and serve topped with cilantro, sesame seeds, and optional red pepper flakes.
Notes
For extra flavor, toast sesame seeds before adding as toppings.