Beef Stroganoff

1. Heat 1 tablespoon of oil in a large skillet. Season half the beef with salt and pepper and saute until brown, about 2 minutes. Transfer to a large plate and set aside. Repeat with remaining oil and beef. Discard excess oil and return skillet to medium-high heat. 2. Melt 2 tablespoons of butter. When the foaming begins to subside, add mushrooms. Cook, stirring occasionally, until well browned, about 7 minutes. Season with salt and pepper. Transfer to plate with beef. 3. Heat 4 tablespoons butter and, just as the foaming subsides, add onion. Cook, stirring, until lightly caramelized, about 5 minutes. Add tomato paste and cook, stirring, until lightly brown, about 1 minute more. Whisk in flour and cook, stirring, for 1 minute. Pour in beef broth and, whisking constantly, bring to full boil. Remove from heat. Whisk in sour cream, mustard, lemon juice and seadon with pepper to taste. Set sauce aside, covered. 4. Meanwhile, bring a large pot of water to boil. Salt generously, and cook egg noodles until tender but not mushy. Drain and transfer to a large bowl. Toss with butter and season with pepper to taste. 5. Add the beef and any juices, mushrooms and parsley to the sauce. If needed, reheat on medium-high (do not boil). 6. Divide the noodles among 4 plates and top with the stroganoff. Serve immediately.