Cook the noodles in a large saucepan of boiling water for about 4 minutes, or according to the packet instructions, until just tender. Drain and set aside.
Cut the steak into thin slices about 1 cm (½ inch) wide. Spread out on a plate and season with salt and pepper.
Mix together the soy sauce, oyster sauce, rice wine and vinegar in a small bowl and set aside.
Spray a large nonstick wok or frying pan with cooking spray and heat over a high heat. Add the steak and stir-fry for about 1–2 minutes until just cooked. Remove with a slotted spoon and set aside. Add the ginger, choi sum, spring onions and bean sprouts and stir-fry for 1–2 minutes.
Return the beef to the pan along with the drained noodles, sauce mixture and the sesame oil. Toss together for about 1–2 minutes until heated through. Serve in warmed bowls.