In small saucepan, combine water, peanut butter, salad dressing, brown sugar, soy sauce, gingerroot and red pepper flakes. Cook over medium-low heat until smooth and warm, stirring frequently. Set aside.
Cook rice noodles as directed on package, adding shrimp during last minute of cooking time. Drain well; return to saucepan.
Add bell pepper, onions and peanut butter mixture to rice noodles and shrimp; toss gently to mix. Serve with lime wedges. If desired, garnish with additional green onion tops.