Place the noodles in a large heatproof bowl, pour over boiling hot water to cover and leave to stand for 10 minutes, or until just tender. Drain and set aside.
Meanwhile, heat the oil in a large nonstick wok or frying pan over a high heat. Add the ginger, garlic, mushrooms, chillies and spring onions and stir-fry for 1–2 minutes. Add the minced pork and stir-fry, breaking it up with a wooden spoon, for about 4–5 minutes until browned.
Stir the soy sauce, hoisin sauce and stock into the pan and cook for 2 minutes. Add the cornflour paste and cook, stirring constantly, for 2–3 minutes until thickened.
Add the drained noodles and tofu and toss together for 2–3 minutes until heated through. Serve immediately.