- In a bowl, combine the sour cream, mustard, tomato paste, capers, Worcestershire sauce, paprika, wine, and salt and black pepper to taste. Whisk together well. Set aside.
- In a large skillet over medium high heat, melt the butter.
- Add the onion and crushed garlic and cook, stirring, until the onion is translucent, about 3 minutes. Reduce the heat to medium.
- Add the tenderloin strips and the beef cube and cook, stirring until cooked through, about 5 minutes.
- Add the mushrooms and cook, stirring, for 3 – 4 minutes. Reduce the heat to medium-low.
- Add the sour cream mixture to the pan and toss the ingredients together well.
- Cover and cook until the Stroganoff is hot, about 5 minutes.