Stir in tomato paste; cook for 1 minute. Sprinkle flour over top and cook for 1 minute.
Whisk in vegetable broth; bring to boil. Reduce heat and simmer for 4 to 6 minutes or until slightly thickened. Remove from heat and stir in sour cream.
Cook noodles according to package directions; drain well.
Toss noodles with mushroom mixture until well coated. Sprinkle with parsley before serving.
Recipe Notes
If mixed mushrooms are not available, use cremini or brown mushrooms or a combination of exotic mushrooms, such as oyster, shiitake and cremini.