In a small bowl, whisk together the soy sauce, oyster sauce, sesame oil, and cornstarch. Set aside.
Cook the lo mein noodles according to package instructions. Rinse under cold water, drain well, and set aside.
Heat 1 tablespoon of avocado oil in a large wok or skillet over high heat. Add the sliced chicken breast and stir-fry until fully cooked. Remove the chicken from the wok and set aside.
Add the remaining 1 tablespoon of avocado oil to the wok. Stir-fry the minced garlic and the white parts of the green onions for 30 seconds until fragrant.
Add the carrots and red bell pepper to the wok. Stir-fry for 3-4 minutes until the vegetables are tender-crisp.
Return the chicken and noodles to the wok. Pour the sauce mixture over the top.
Toss continuously for 2 minutes until everything is evenly coated and heated through.
Remove from heat, garnish with the green parts of the sliced green onions, and serve immediately.