Delicious Pork Tenderloin With Sour Cream and Mushroom Sauce

Slice tenderloins into about eight pieces; flatten each medallion slightly with the heel of your hand. In a large skillet or sauté pan over medium heat, melt one tablespoon of butter with one tablespoon of oil. Cook mushrooms until tender, about five minutes; then add onion and cook for one minute longer. Transfer the mushrooms and onions to a plate; set aside. Pour off the excess liquids from the pan. Melt the remaining butter with oil over medium heat. Add pork tenderloin medallions and cook for about three minutes on each side or until browned. Sprinkle the pork lightly with salt and pepper. Pour in wine and half of the chicken broth. Reduce heat to low, cover, and cook for 15 minutes. Transfer the pork to a serving dish and keep warm. Stir flour into the remaining chicken broth until smooth. In the skillet over medium heat, stir in the flour-and-broth mixture. Cook, stirring, until the sauce is thickened. Taste and add salt and pepper, as needed. Stir in the sour cream, parsley, the cooked mushrooms, and onions. Heat through but do not boil. Serve sauce with the pork slices.