Step 1

Place the meat between two pieces of plastic wrap and pound until it is about 1/8 inch thick. Do this firmly, but don't wail on the meat or you will tear it. Trim the cutlets to an even shape if you want.

Step 2

Set a large sauté pan over high heat for 1 minute, then add the mushrooms to the hot, dry pan. Shake them around so they don't stick too much and cook the mushrooms until they give up their water, about 3 or 4 minutes. Add 2 tablespoons of the bacon fat and onions and stir-fry everything until the onions begin to brown, about 3 minutes. Remove the mushrooms and onions and set aside.

Step 3

Dust the cutlets in flour if you want to. Add the remaining bacon fat to the sauté pan and let it heat up over medium-high heat. Do not let it smoke. Sear the cutlets for 90 seconds on the first side. Keep them from curling up with a spatula. Flip the cutlets and sear another 90 seconds for medium doneness. Remove the cutlets to a plate. (If you have a lot of them, set the plate in the oven and set it to "warm.")

Step 4

Add the 2 tablespoons flour and mix with the fat in the pan. Turn the heat to medium and let the flour-and-fat mixture cook until it is the color of coffee-with-cream. Slowly pour in the stock, plus any juices that have come off the cutlets while they rest. You should have a thick gravy. If it is thin, let this boil down a minute or two. If it is really thick, turn off the heat, wait for the sauce to stop bubbling and stir in the cream. Add the mushrooms and onions back to the pan and toss to coat in the sauce. Add salt and black pepper to taste. Pour this over the cutlets and serve at once.