Cook the noodles in a large pan of boiling water for 3-5 mins, then drain and put them in cold water. Drain thoroughly, toss them with 1 tbsp of the sesame oil and set aside.
Combine the beef with all the marinade ingredients and ½ tsp salt, mix well and then leave to marinate for about 10 mins.
Heat a wok over a high heat. Add 1 tbsp of the sesame oil and, when it is very hot and slightly smoking, add the beef. Stir-fry for about 2 mins and then transfer to a plate.
Wipe the wok clean. Reheat the wok until it is very hot, then add the remaining sesame oil. When the oil is slightly smoking, add the garlic and stir-fry for 10 secs. Then add the mangetout and stir-fry for about 1 min.
Add the noodles, soy sauces, rice wine or Sherry, pepper, sugar, spring onions and 1 tsp salt. Stir-fry for 2 mins. Return the beef and any juices to the noodle mixture.
Stir-fry for about 3-4 mins or until the beef is cooked. Add 1 tsp sesame oil and give the mixture a few final stirs. Put on a warm platter and serve immediately.