After a piping hot bowl of this decadent dish, all that needs to be said is spasiba (thank you).
Yield: 4 servings
Add 1 tablespoon butter to a pan on medium heat. When foam subsides, add onions, and season with salt and pepper. Cook until soft, 8–10 minutes. Remove from pan, and reserve.
Add 1 tablespoon butter to pan with mushrooms. Sauté until mushrooms are golden brown, 10 minutes. Remove from pan, and reserve.
Add 2 tablespoons butter to pan. When butter is melted, add flour. Stir mixture, and cook 1 minute. Add stock and cognac to pan, whisking constantly. In 3–4 minutes, when mixture is thick and smooth, add sour cream. Whisk well, and remove from heat. Add reserved onions and mushrooms to pan with sauce, and mix.
Pat beef dry, and season with salt and pepper. Add 1 tablespoon oil to a pan on medium-high heat. Add beef, and cooked until browned on all sides, 3–4 minutes. Add beef to sauce. Top with chives, and serve.