Beef Stroganoff With Mushrooms And Onions

["Follow the recipe for Flaming Onions, but use only one large sweet onion, and use brandy. Do not adjust any other ingredient amounts.", "Prepare this recipe, and set aside.", "In a mixing bowl, mix the mustard, the sugar, and a little pinch of salt with 1 tablespoon of hot water to form a paste. Divide the paste in half. Set aside.

Add the sliced steak to one half of the paste in the bowl, stirring the paste in thoroughly, and allow to sit while you prepare the rest of the recipe.", "Heat the butter in a medium saute pan. Add the sliced mushrooms and cook over medium to low heat. Add a little salt and pepper, and continue to saute until just a little liquid is left.", "Add the sherry, and allow the mushrooms to cook on low heat for a few minutes. When most but not all of the sherry is evaporated, take the mushrooms off the heat.", "In a heated frying pan, over medium high heat, sear half the meat slices. Essentially, flash-fry them. As soon as the slices are all in the pan, immediately turn the slices over in the order that you placed them in the frying pan. Then, just as quickly, take the meat slices out in the same order you started and place on a platter so the meat juices can accumulate. Then, sear the second half of the slices the same way. Cover the meat slices and set aside briefly.", "Add the mushrooms to the Flaming Onion recipe. Mix together.", "Add the other half of the mustard paste to the onions and mushrooms. Then add the sour cream and yogurt by the tablespoonful. Mix together and adjust seasoning if necessary. Add gratings of nutmeg and take a final taste. Allow the stroganoff to simmer for a few minutes to allow the sauce to develop flavor. Add the meat slices and the accumulated juices and cook just enough to heat them. Serve over rice, noodles, couscous, or with matchstick potatoes."]