Marinade the steak with 1 tsp light soy sauce, 1 tsp vegetable oil, and 1 tsp cornstarch and set aside
Combine oyster sauce, light soy sauce, dark soy sauce, fish sauce, caster sugar, and ground white pepper in a bowl and set aside
If using dried noodles, undercook them and toss with a little oil after draining. If using fresh rice noodles, ensure they are at room temperature or rinse briefly under hot tap water and drain
Heat a little oil in a wok over high heat and add the beef, cooking until caramelised around the edges and just cooked through, then remove and set aside
Stir in the garlic, adding a little extra oil if needed, followed by the Asian greens and stir-fry for 30 seconds
Spread the noodles around the wok and pour the sauce mixture over, gently mixing to coat everything evenly
Return the beef to the wok and push everything to one side
Add a bit more oil if needed, then pour in the beaten egg, scrambling it into small pieces
Toss everything together gently and cook until slightly caramelised
Adjust seasoning to taste and serve immediately with homemade chilli oil
