Spray 5-quart slow cooker with cooking spray. In slow cooker, mix broth, chicken, soy sauce, pepper, garlic and gingerroot.
Cover; cook on Low heat setting 3 hours.
Stir rice noodles into soup. Cover; cook 15 minutes longer. Remove gingerroot. Top individual servings with onions, bean sprouts, chiles and cilantro. Serve with lime wedges.