Cook lo mein noodles according to package directions. Drain and set aside.
In a small bowl, whisk together soy sauce, oyster sauce, sesame oil, cornstarch, and water to make the sauce. Set aside.
Heat vegetable oil in a large skillet or wok over medium-high heat. Add chicken and stir-fry until cooked through and no longer pink.
Add minced garlic and ginger to the skillet and stir-fry for about 30 seconds until fragrant.
Add broccoli, carrots, and bell pepper to the skillet. Stir-fry for 3-5 minutes until vegetables are tender-crisp.
Add the cooked noodles and the prepared sauce to the skillet. Toss everything together until the noodles and vegetables are well coated and the sauce has thickened.
Stir in chopped scallions just before serving.
Notes
Serve immediately. You can add other vegetables like snap peas, mushrooms, or water chestnuts if desired.