Slice beef into ¼ inch strips and marinate for 10 minutes in baking soda, light soy sauce, dark soy sauce, white pepper, cornstarch, and neutral oil.
To make the stir fry sauce, mix together light soy sauce, dark soy sauce, oyster sauce, sugar, Shaoxing wine, MSG (optional) and set aside. Prepare all vegetables and separate the fresh rice noodles. Set them all aside on a tray.
In a large nonstick pan or wok over high heat, add 2 tablespoons of neutral oil and sear the marinated beef for 2-3 minutes and remove to a plate, discarding any excess oil.
Add 1 tablespoon of oil to the pan over high heat. Add the separated rice noodles and toss for 30 seconds. Add a tablespoon of light soy sauce and 2 teaspoons of dark soy sauce around the edge of the pan. Toss and cook until the noodles are slightly charred and have absorbed the soy sauce, about 1 minute. Remove to the plate with the beef.
Add 1 tablespoon of oil over medium high heat and saute onions and garlic for 30 seconds. Next, add scallions and bean sprouts. Cook for another 30 seconds until scallions have a nice charred color.
Turn the heat to high. To the vegetables, add back your beef, rice noodles, and sauce. Cook for 2-3 minutes until the sauce has absorbed completely into the noodles, beef and vegetables. Drizzle with sesame oil, toss and enjoy!
