Slice the beef across the grain into thin strips. Put the beef strips into a gallon ziplock bag and add the marinade and close bag. Squish the marinade into the beef and let sit for 30 minutes. Then add the 1 1/2 tbsp. oil, squish around again and let marinate another 30 minutes.
While beef is marinating, prepare the onions. Wash and slice all the green onions lengthways, then into 2 inch pieces. Mince garlic.
Mix together the sauce ingredients and set aside. When the beef has finished marinating, heat the wok and add 1 cup of oil. When oil is 350 degrees carefully slide the beef strips into the wok. About 7 pieces at a time. Fry until the beef changes color and browns a bit. Remove from oil and drain on paper towels. When all the beef is cooked pour out all the oil into a pyrex safe dish except for 2 tbsp. When it's nice and hot again stir-fry the garlic and green onions. Takes about 2-3 minutes.
Before the onions are all the way cooked push them up to the sides of the wok and add the sauce. Stir until thick about 1 minute. Then add the beef and stir all together.
Follow the directions to fry the Maifun noodles. Serve the Mongolian Beef on top of the noodles or sticky rice.