Chop scallions, separating green part from white part. Saute garlic, ginger and white part of scallions in oil in skillet or wok for 30 seconds. Add meat, saute, breaking up with a spoon. Cook until no longer pink, about 5 minutes. Add soy sauce, waterchestnuts, and red pepper flakes. Bring to a boil, stirring. Add boiling water and noodles and stir well. Cover and cook over medium heat until noodles are tender, about 7 minutes. Garnish with chopped green scallion parts.