Heat the oil in a wok or large frying pan over high heat.
Add the sliced beef and stir-fry for 2–3 minutes until browned. Remove and set aside.
Add minced garlic to the pan, then toss in the baby corn, sugar snap peas, asparagus and red pepper. Stir-fry for 3–4 minutes.
Return the beef to the pan along with pak choi leaves.
Add soy sauce and oyster sauce (if using). Stir to coat everything evenly.
Cook for another 1–2 minutes until pak choi is wilted but still vibrant.
Sprinkle with red chilli flakes if desired and serve hot.