1Cook and drain noodles as directed on package; cover to keep warm.
2Meanwhile, in small bowl, beat peanut butter, gingerroot, pepper flakes and 2 tablespoons of the soy sauce with wire whisk until blended. Gradually beat in remaining 2 tablespoons soy sauce and the water until smooth. Set aside.
3In 12-inch nonstick skillet, heat oil over medium-high heat. Cook broccoli, mushrooms, carrots and bell pepper in oil 4 to 6 minutes, stirring occasionally, until vegetables are crisp-tender. Add chicken; cook and stir until hot.
4Reduce heat to medium. Stir peanut butter mixture; stir into mixture in skillet. Stir in cooked noodles until coated. Cook and stir until hot. Sprinkle with peanuts.