1.Add noodles to a large pan of boiling water; boil, uncovered, for 1 minute; drain.
2.Meanwhile, heat half the oil in a wok or large frying pan, add lemon grass, chilli, garlic and onion, stir-fry for about 1 minute or until fragrant. Add beans, stir-fry until almost tender. Remove from pan.
3.Heat remaining oil in the wok, stir-fry lamb, in batches, until browned. Return lamb and onion mixture to pan with sauces, stock and noodles; stir-fry until hot. Add herbs, toss gently.
4.Serve immediately, sprinkled with peanuts.
Lemon grass is available chopped in jars in the Asian section of supermarkets. Ask your butcher to slice the lamb thinly across the grain for a more tender result. This recipe is best made just before serving.Note