SOAK THE NOODLES in a large bowl of warm water for 15 minutes. When they are soft, drain them and discard the water. Cut them into 3-inch lengths using kitchen scissors or knife. Put 1 tablespoon of oil into a hot wok or pot, then add the scallions and garlic and stir-fry quickly for a few seconds. Add the meat and stir-fry until it is cooked. (This should take between 5 and 10 minutes.) Then add all the sauce ingredients, except the sesame oil and cook the mixture over a gentle heat for about 5 minutes. Now add the drained noodles and sesame oil and cook the mixture for a further 5 minutes. Ladle some noodles and sauce into individual bowls or into one large serving bowl, and serve at once.