Sprinkle turkey drumsticks with salt and pepper. In 5- to 6-quart slow cooker, place drumsticks. In small bowl, mix plum sauce, onions and soy sauce. Pour over turkey.
Cover; cook on Low heat setting 8 to 10 hours.
About 25 minutes before serving, remove turkey from slow cooker; place on serving platter. Cover with foil to keep warm. Remove any fat from liquid in slow cooker.
In small bowl, blend water and cornstarch until smooth. Stir into liquid in slow cooker. Increase heat setting to High. Cover; cook 15 to 20 minutes longer or until sauce has thickened. Remove turkey meat from bones. Serve turkey with sauce over noodles.