1.Heat half of the oil in a wok or large non-stick frying pan; stir-fry steak, in batches, until browned. Remove from the wok.
2.Heat remaining oil in wok; stir-fry onion until softened. Add garlic and ginger, stir-fry until fragrant. Add shiitake and oyster mushrooms; stir-fry until just tender. Add enoki mushrooms and chilli; stir-fry until just combined.
3.Meanwhile, pour boiling water over noodles to separate; drain well.
4.Return steak to wok with noodles and remaining ingredients; stir-fry until mixture boils and thickens slightly.