Spray 12-inch skillet or 5-quart Dutch oven with cooking spray; heat over medium-high heat. Add onion; cook and stir 2 to 3 minutes or until crisp-tender.
Stir in water, broth, uncooked noodles, frozen peas and paprika. Heat to boiling. Reduce heat to medium-low; cover and simmer 6 to 8 minutes, stirring occasionally, until noodles are desired doneness and liquid is almost absorbed.
Stir in beef and sour cream. Cook 1 to 2 minutes longer, stirring constantly, just until hot. Sprinkle with green onions.