Slice Pork tenderloin into several medallions, about 1-inch thick.
On a large plate or use a zip lock bag (easier to toss out) mix flour, garlic powder, onion powder, paprika, and salt/pepper.
Dredge Pork medallions in seasoned flour and sear them in 1/2 tbsp olive oil on Medium-High heat until golden brown. Set aside to a warm place.
Reduce heat to medium, add a tablespoon of butter and remaining olive oil.
Add sliced onion and mushrooms to the pan.
Sauté until mushrooms are browned and onions caramelized.
Add garlic and cook for a minute.
Add 2 tablespoons of flour or corn starch and mix well.
Add Marsala or white wine and chicken broth, scraping up all the bits in the bottom of the pan.
Stir in 1/2 cup sour cream
Return cooked pork to the pan and simmer for 1 – 2 minutes until the sauce thickens into a gravy consistency (it will thicken more as you serve).
Adjust salt and pepper, to taste.
Cook your favorite pasta according to the directions on the package. Add to the pan and mix with creamy mushroom sauce.
Garnish with chives or fresh parsley.