Ask butcher to cut beef into strips. Season beef generously with salt and pepper.
Cover and let stand for 2 hours in cool place.
In large skillet, whisk flour and 3 tablespoons butter over low heat until mixture
bubbles and forms a smooth paste. Slowly add beef broth, stirring constantly until
mixture thickens. Let boil for 2 minutes.
Reduce heat and add sour cream alternately with tomato juice, still whisking.
Simmer slightly 1 minute; do not let boil.
In separate skillet, quickly brown beef and onion in remaining 1 tablespoon butter
over medium heat. Add contents of meat pan to sauce; season with salt and pepper.
Simmer very gently or cook over hot water in double boiler for 20 minutes.