In a small bowl, mix together the soy sauce, dark soy sauce, oyster sauce, sesame oil, brown sugar, and water. Set aside.
Thinly slice the steak against the grain and place it in a medium bowl. Add the baking soda, cornstarch, dark soy sauce, brown sugar, and avocado oil. Toss until the steak is evenly coated, then marinate for at least 20 minutes.
Heat 1–2 tablespoons of oil in a large wok or skillet over high heat. Add the steak in a single layer and sear for 1–2 minutes per side, or until browned and just cooked through. Transfer to a plate and set aside.
In the same wok, add a little more oil if needed. Stir-fry the ginger and onion for 1–2 minutes, or until the onion begins to soften. Add the garlic and cook for 30 seconds, until fragrant.
Add the fresh rice noodles and green onions. Gently toss for about 1 minute to loosen the noodles. Pour in the prepared sauce and continue tossing until the noodles are evenly coated.
Add the bean sprouts and cooked steak. Toss everything together for 1–2 minutes, just until the bean sprouts are slightly softened and the beef is heated through.
Serve immediately and enjoy!
