Strange, everyone is talking about beef stroganoff and no one is posting anything resembling a recipe. I've been doing a variation using hamburger for years, which I call HAMBURGER STROGANOFF.
Start by heating some vegetable oil in a large skillet. Over medium heat, cook a chopped onion until softened, about 3 minute, then add a half pound of sliced mushrooms and cook until they are nicely browned, figure another five minutes. Add a pound of ground beef, the leaner the better, and cook until the meat loses it's pink color, stirring to break up the meat.
To this, add about a teaspoon of Worcestershire Sauce and freshly ground pepper and salt, but not too much of these, a quarter teaspoon should do. Stir in two tablespoons of flour, and cook for another minute so that the flour loses it's starchy taste. Add one can beef broth, about 1 1/4 cups if you make your own, and bring to a simmer, cooking for another minute while the flour thickens the sauce.
Taking the skillet off heat, add 1/2 cup sour cream, stirring to blend. Put back on heat for just a half minute or so to heat the sour cream (don't bring back to a boil, or the sour cream will curdle). Serve over hot egg noodles or rice, and sprinkle with fresh chopped dill. Serves four, unless you really love this stuff like der Brucer and I do, in which case it only serves three.