BEEF STROGANOFF

Steps:

• For the stroganoff: Preheat a large skillet over medium heat for 3 to 4 minutes. Raise the heat to high and heat 1 tablespoon oil. Season half the beef with salt and pepper, add to the skillet, arranging it in a single layer, and cook without stirring until well-browned and still pinkish inside, 1 to 2 minutes. (It is key to only partially cook the meat at this stage, since it will be finish cooking later in the sauce.) Transfer to a large plate and set aside. Repeat with the remaining oil and beef. Discard any excess oil.
• Return the skillet to medium-high heat. Melt 2 tablespoons of the butter and, when the foaming begins to subside, add the mushrooms and cook, stirring occasionally, until well-browned, about 7 minutes. Season with salt and pepper to taste. Using a slotted spoon, transfer to the plate with the beef.
• Heat the remaining 4 tablespoons butter in the skillet; when the foaming begins to subside, add the onion and cook, stirring, until lightly caramelized, about 5 minutes. Add the tomato paste and cook, stirring, until lightly browned, about 1 minute more. Whisk in the flour and cook, stirring, for 1 minute. Pour in the beef broth and, whisking constantly, bring to a full boil. Remove from the heat. Whisk in the sour cream, mustard and lemon juice and season with pepper to taste. Set the sauce aside covered.
• Meanwhile, for the noodles: Bring a large pot of water to a boil, salt generously, and cook the noodles until tender but not mushy. Drain and transfer to a large bowl. Toss with the butter and season with pepper.
• Add the beef and any juices, mushrooms and parsley to the sauce and reheat over medium heat until just hot. (Do not boil.) Divide the noodles among 4 plates and top with the stroganoff. Serve immediately.