Cook, stirring, until meat is no longer pink, about 5 minutes. Remove and set aside.
To skillet add and sauté onions, mushrooms and garlic until vegetables are tender. Add broth, Worcestershire sauce and pepper and bring to a boil. Reduce heat and simmer until liquid has reduced by half.
Stir cornstarch into wine until dissolved. Add to skillet and cook, stirring, over medium heat until mixture has thickened, about 3 minutes. Return meat to mixture and stir until heated through. Remove from heat.
Add sour cream and mustard to skillet and stir until blended. Serve over cooked noodles, sprinkled with parsley.
Tip:Partially freeze meat to make slicing easier.
If reheating stroganoff mixture, do not bring it to a boil.
Instead of wine you can use beef broth and 1 Tblsp red wine vinegar.