1.Place noodles in heatproof bowl, cover with boiling water, stand 5 minutes; drain. Heat oil in wok or large pan, add beef, cook until browned on both sides and tender, remove. Cool beef, cut into thin slices. Add onion to wok, stir-fry until onion is lightly browned. Add peas, sprouts, shallots, bok choy, chillies and ginger, stir-fry 2 minutes. Return beef to wok with noodles, cucumber and dressing, toss over heat until heated through. Top with coriander.
2.For dressing, combine all ingredients in jar; shake well.
Best made just before serving. Not suitable to freeze or microwave.Note