Soak noodles in hot water 10 minutes; drain and set aside.
Sauté diced onion in hot oil in a large skillet over medium-high heat 5 minutes or until tender. Add carrot and next 4 ingredients; cook, stirring occasionally, 2 minutes.
Stir together broth and cornstarch until smooth; add to chicken mixture. Add soy sauce and oyster sauce; bring mixture to a boil, and cook 1 minute. Remove from heat; serve over noodles. Garnish, if desired.