Put noodles in a medium heatproof bowl and cover with boiling water and set aside for 2 minutes and then drain and separate the noodles and set aside.
Put the sweet chilli sauce, lime juice and soy sauce in a small bowl, stir to combine and set aside.
Brush a little oil over a large wok and heat on high until the wok is hot and then add half of the beef and stir fry for 2 minutes or until beef is almost cooked and then transfer to a plate.
Brush the wok with a little more oil and reheat wok on high and repeat with remaining beef and then remove beef from wok and add to the first batch of beef.
Brush the wok with remaining oil and heat on medium-high and add the capsicum, zucchini, mushroom, garlic, ginger and choy sum stalks and stir fry for 2 minutes and then add the water and choy sum leaves and cook covered tossing twice for 2 minutes or until the vegetables are just tender.
Add noodles, beef and spring onion to the wok and toss to combine and then add the sauce and toss once more to combine and heat through.
Top with coriander leaves to serve and accompany with lime wedges.