Jackie Kennedy's Beef Stroganoff

Season the beef with salt and pepper and place in a covered container in the refrigerator for 2 hours.

Melt 3 tablespoons of the butter in a large skillet over medium-low heat. Whisk the flour into the melted butter and mix until bubbles form and the mixture is smooth. Slowly whisk in the beef broth. Stir constantly until the sauce thickens, about 5 minutes. Reduce the heat to low and let the sauce simmer.

Heat another skillet over medium-high heat. Add the remaining butter. When melted, add the beef and onion. Cook, stirring constantly, until the meat starts to brown. Transfer the meat mixture to the sauce.

Add the tomato juice and mushrooms (if using) to the stroganoff and let simmer on low heat for 15 minutes. Stir the sour cream into the liquid and let heat through (do not let it boil).

Serve hot.