Leftover Turkey (or Roast Chicken) Sort-of-Stroganoff

Directions

1. Saute the onion for several minutes over medium heat, stirring, in 1 tablespoon of the butter and in the bacon fat. You can use all butter instead, or substitute oil if you prefer.
2. Add the mushrooms with a pinch of salt, and sauté until they're soft and brown, and have released a fair bit of liquid. Remove the sautéed vegetables with a slotted spoon and set them aside.
3. Add the remaining butter to the pan and melt over medium heat, stirring. Slowly sprinkle in the flour, stirring for several minutes to combine, until the mixture starts to brown a bit more. Add the mushroom powder, if using, and stir well to distribute it.
4. Gradually add the turkey or chicken broth, whisking or stirring continually to incorporate all the ingredients. Add the mustard, wine, and, if you’re using it, the Worcestershire sauce. Stir well.
5. Stir in the onion and mushrooms and cook over medium heat for another 2-3 minutes.
6. Over medium heat, add the sour cream or Greek yogurt and stir it vigorously until everything is combined. Watch it carefully, as the sauce should not boil. Test and correct the seasoning as needed.
7. Stir in the turkey or chicken, and simmer just until it's heated through. If there's not enough sauce, add a touch more stock. When anything is "over toast" more sauce is always better.
8. Serve over toasted thickly sliced bread. This is also good over brown rice or leftover mashed potatoes - or under mashed potatoes in a casserole, then popped under the broiler for a quick shepherd's pie.
9. You can also serve this over noodles, or stir it into noodles, top with small cubes of bread, drizzle some melted butter over it and pop it into the oven until the bread cubes turn into dark, crunchy croutons, if you like casseroles.
10. However you choose to go . . . . I hope you enjoy this. ;o)
11. N.B. I get excellent and reasonably priced mushroom powder from nuts.com. In fact, I almost never use dried mushrooms in any other form these days. The powder is so darned convenient, and packs a wallop of flavor. I put it in any dish where mushrooms might be nice (but aren't essential), such as just about any meat or sausage and tomato dish, especially pasta sauces and braises. And let's not forget the soups that love mushroom powder, especially chicken with wild rice, chicken noodle, beef and barley, and mushroom barley (yes, add it when you're also using mushrooms for a nice flavor boost).
12. This is (I think) the first recipe I posted on Food52, as part of the "Your Best Thanksgiving Leftovers" contest in November 2009.