1. Sprinkle the pork with the salt and pepper. Place the flour in a shallow bowl or on a piece of wax paper. Dredge the pork cutlets in the flour until coated, then shake off the excess.
2. Heat the butter and oil in a large skillet over medium-high heat until bubbly. Add the pork and cook, turning once, until browned, about 4 minutes. Transfer to a plate and keep warm.
3. Add the sherry, orange juice concentrate and tarragon to the skillet drippings. Cook over medium heat, stirring, until reduced by one-third. Reduce the heat to low. Stir in the sour cream and cook for 2 minutes; do not boil.
4. Return the pork to the skillet and cook, turning to coat, for 2 minutes. Arrange the pork on a serving platter, drizzle with the pan sauce and serve.
Variation
You can use pork chops instead of pricier pork tenderloin. Select thin chops so they cook quickly and increase the cooking time in step 2 to 6 minutes (or 8 minutes for thicker chops).
Tip: Prevent Curdling
Turning the heat to low before adding the sour cream is one way to prevent the sauce from curdling. Another is to return the pork to the skillet after the sauce is reduced, cook it for 2 minutes, then stir in the sour cream.