In a medium bowl, combine beef and marinade ingredients. Let marinate for at least 30 minutes.
In a small bowl, combine the sauce ingredients. Set aside.
Make sure the noodles are somewhat separated and not stuck in a big clump. Soften in microwave or blanch briefly in a pot of boiling water, if necessary.
In a wok or large frying pan on medium high heat, add 1 tablespoon oil, add the beef and stir fry until 70-80% cooked.
Add 2 tablespoons oil. Add onions and white parts of green onion. Stir fry for 1-2 minutes.
Evenly distribute noodles and stir fry for 1 minute. Add the sauce. Stir fry, making sure to scrape the bottom of the wok and that the noodles are evenly coated with the sauce and heated through.
Add bean sprouts, beef and any drippings. Stir fry for another minute. Turn off the heat and stir in green onion and drizzle with sesame oil.