Begin by slicing the boneless chicken into thin strips and placing them in a bowl. Add 1 tablespoon of soy sauce, 1 teaspoon of cornstarch, and 1 teaspoon of sesame oil. Mix well to coat the chicken evenly and let it marinate for about 5 to 10 minutes while you prepare the other ingredients.

While the chicken is marinating, bring a large pot of water to a boil. Add the lo mein noodles and cook according to the package instructions, usually around 4-5 minutes, until tender yet firm. Once cooked, drain the noodles and toss them with a splash of sesame oil to prevent sticking, then set aside.

In a separate bowl, whisk together the sauce ingredients: 3 tablespoons of soy sauce, 1 tablespoon of oyster sauce, 1 tablespoon of hoisin sauce, 1 teaspoon of brown sugar, and 1/4 cup of chicken broth or water. Set it aside for later use.

Heat 2 tablespoons of vegetable oil in a hot wok or large skillet over medium-high heat. Once shimmering, carefully add the marinated chicken in a single layer. Sauté for about 5-7 minutes, until the chicken is golden brown and cooked through. Remove the chicken and keep it warm.

In the same skillet, add the minced garlic and optional grated ginger, cooking for about 30 seconds until fragrant. Next, toss in the sliced bell peppers, shredded carrots, and snap peas. Stir-fry these veggies for 3-4 minutes until they are tender-crisp.

Return the sautéed chicken to the skillet with the vegetables, then pour in the prepared sauce. Stir everything together and allow it to simmer for about 1-2 minutes until the sauce thickens slightly.

Now, add the cooked lo mein noodles and sliced green onions to the skillet. Gently toss everything together for another 1-2 minutes, ensuring the noodles are warmed through and evenly mixed with the sauce and vegetables.