1.Place noodles in large heatproof bowl, cover with boiling water. Stand until just tender, drain. Rinse under cold water, drain.
2.Heat oil in wok or large frying pan, stir-fry onion, garlic, asparagus and capsicum until just tender. Add noodles, sauces, vinegar and stock, stir-fry until sauce boils.
3.Add tofu and spinach, stir-fry until spinach just wilts. Serve topped with nuts.