Add Worcestershire, Dijon, butter, and flour; stir to coat. Gradually pour in beef broth, simmer until thickened, then stir in sour cream and Greek yogurt.
Return beef to the pan, cook for 5 minutes, then season with salt and pepper to taste. Garnish with chopped parsley and serve over your choice of noodles, potatoes, or spirals.
Notes
For a richer flavor, use a splash of red wine or beef gravy if desired.