Mix sherry, soy, teriyaki sauce, sugar, 2 teaspoons sesame oil and ginger in small bowl; reserve sauce.
Cook noodles according to package directions. Drain; toss with remaining sesame oil.
Heat vegetable oil in large nonstick skillet over high heat. Add garlic and white part of scallions; stir-fry 30 seconds, until fragrant. Add chicken to skillet; stir-fry 2 to 3 minutes or until partially cooked.
Add vegetables and reserved sauce to skillet; stir-fry 3 to 4 minutes or until heated through.
Stir cornstarch and water in small bowl until smooth; stir into skillet. Cook until mixture has thickened, about 1 minute.
To serve, place noodles on serving platter. Top with chicken, vegetables and remaining scallions. Serve immediately.