In a shallow bowl, add 1 tablespoon of flour and the salt, mix together. Coat the beef strips with the flour.
In a large non stick pan, melt 2 tablespoons of butter, when hot, add the beef strips and brown on each side.
Add the mushrooms, onion, and garlic. Cook for 3-4 minutes or until onion is just barely tender. Remove beef, mushrooms, and onion from pan to a plate.
Add 2 more tablespoons of butter to the pan, when melted, stir in 3 tablespoons until smooth. Stir in tomato paste. Slowly stir in beef stock, stir until mixture thickens.
Return the beef, mushrooms, and onion to the pan.
Stir in the sour cream and wine. Heat through for just a few minutes or until hot.
Serve over hot buttered noodles. Enjoy.