1.In a small bowl combine chicken broth, dark soy sauce, soy sauce, oyster sauce, and sugar. Mix well and set aside. In a medium bowl add chicken and season with salt, pepper, and garlic powder. Mix well then add cornstarch and mix again, set aside.
2.In a wok on medium heat, add oil once hot then add chicken and cook until browned and cooked through. Transfer to a plate and set aside.
3.Add garlic and onion and cook for 2 minutes. Add the cooked chicken and stir. Add carrot, mushrooms, and green beans and cook for 3 minutes. Add napa cabbage and season with salt, pepper, and garlic powder. Cook for 1 more minute until tender.
4.Add the bowl of sauce and mix together. Bring the sauce to a boil then add dry rice noodles and stir until all the noodles are coated with the sauce. Keep on stirring and cooking until the noodles are tender, 3-4 minutes.
5.Sprinkle green onions and stir until combined. Serve immediately with lemon wedges.