30 minutes before you are going to make the stroganoff, remove meat from refrigerator and allow to come to room temperature (for more even cooking).

In a large skillet over medium high heat, add 2 tablespoons of butter and bring to sizzle. Salt and pepper meat. Add meat to cover bottom of pan but do not overcrowd. Quickly brown on both sides and remove to plate. They should not be completely cooked at this point. Continue to brown remaining beef in batches.

Add 1 tablespoon of butter or oil to pan, and add onions and cook until lightly browned and translucent, about 8 minutes. Add mushrooms and season with salt and pepper over medium high heat. Sauté until lightly browned and they have given up most of their liquid. Add tomato paste, Worcestershire sauce, and flour and stir to incorporate and cook for 1 minute. Add wine and bring to boil and cook for 2 minutes. Add stock and bring to boil. Reduce heat to medium and cook for 15 minutes. (At this point, you can reserve the onions and mushrooms until you are 15 minutes away from serving in the refrigerator. To serve, reheat sauce and add beef and continue following recipe.) Add beef and any accumulated cooking juices. Taste for seasoning. Add sour cream and cook until slightly thickened about 5 minutes. Sprinkle with parsley or dill and serve over noodles.