Begin by cutting boneless, skinless chicken breasts into thin strips. In a bowl, mix together soy sauce, cornstarch, rice wine vinegar, sesame oil, ground ginger, and white pepper. Add the chicken, ensuring it's well-coated, and let it marinate for at least 30 minutes.

While the chicken marinates, bring a large pot of water to a brisk boil. Add lo mein noodles (or spaghetti) and cook according to package instructions until al dente, typically about 3-5 minutes. Drain and rinse under cold water to stop the cooking process.

In a separate bowl, whisk together soy sauce, oyster sauce, brown sugar, cornstarch, sesame oil, rice wine vinegar, chicken broth, and white pepper until smooth.

Heat a wok or large skillet over medium-high heat and add vegetable oil. Once hot, carefully add the marinated chicken and stir-fry for 5-7 minutes, or until it’s golden brown and cooked through.

In the same wok, add more oil if needed, then toss in minced garlic and ginger, stirring until fragrant (about 30 seconds). Add bell peppers, mushrooms, shredded carrots, and any other desired vegetables. Stir-fry for 3-4 minutes.

Return the cooked chicken to the wok with the sautéed vegetables. Pour the prepared sauce over the mixture, tossing everything to combine. Add the cooked noodles gradually, tossing them to ensure they’re evenly coated.

Once everything is well mixed and heated, turn off the heat. Plate your Garlic Chicken Lo Mein, and garnish with sliced green onions. Serve immediately.