01 - Combine the sliced beef with soy sauce, cornstarch, Shaoxing wine, and oil in a bowl. Mix thoroughly and marinate for 10–15 minutes to tenderize.
02 - Whisk together light soy sauce, dark soy sauce, oyster sauce, sugar, and water in a small bowl until well combined. Set aside for later use.
03 - Gently separate refrigerated noodles. If stiff, steam or microwave briefly to soften without overcooking.
04 - Heat 1 tbsp vegetable oil in a large wok over high heat. Sear the marinated beef for 1–2 minutes until just browned on the outside. Remove from wok and set aside.
05 - Add another 1 tbsp oil to the wok. Stir-fry the sliced onions and most of the spring onions (reserving some for garnish) for 1–2 minutes until fragrant and slightly softened.
06 - Add the rice noodles to the wok, spreading them evenly across the surface. Let them sear undisturbed for 1 minute to develop a slight char and enhance flavor.
07 - Pour the prepared sauce over the noodles and quickly toss to coat evenly. The noodles should absorb the sauce and develop a glossy appearance.
08 - Return the seared beef to the wok along with the bean sprouts. Stir-fry everything together for 1–2 minutes until heated through and well combined.
09 - Garnish with the reserved spring onions and serve immediately while hot for the best texture and flavor.