In a mixing bowl, combine thinly sliced boneless skinless chicken with soy sauce, cornstarch, and sesame oil. Toss until the chicken is well-coated and let it marinate for 5-10 minutes.

While the chicken marinates, bring a pot of salted water to a boil and cook the lo mein noodles according to package directions, about 4-5 minutes. Drain and toss with sesame oil to prevent sticking.

In a small bowl, whisk together soy sauce, oyster sauce, hoisin sauce, brown sugar, chicken broth, and toasted sesame oil until well combined.

Heat a large wok over medium-high heat and add vegetable oil. Once hot, add the marinated chicken in a single layer. Cook for 5-7 minutes until browned and cooked through, then set aside.

In the same wok, add more vegetable oil if necessary and toss in minced garlic and grated ginger. Sauté for about 30 seconds until fragrant.

Add sliced bell peppers, shredded carrots, and snap peas. Stir-fry for 3-4 minutes until crisp-tender.

Return the cooked chicken to the wok. Pour in the sauce and simmer for 1-2 minutes, stirring well.

Finally, add cooked lo mein noodles and sliced green onions, tossing gently to combine. Serve immediately.