Method

• 01
  Dry the steak well and season with salt and pepper. Heat the oil in a skillet over medium heat until just beginning to smoke.
• 02
  Add the steak to the skillet and sear on all sides, until a crust has developed and the internal temperature of the beef registers 125℉ about 8 to 10 minutes.
• 03
  Reduce heat if the brown bits on the bottom begin to burn. Transport the steak to a plate and set aside to rest for at least 5 minutes.
• 04
  By cooking the steak first and then slicing, this prevents the beef from overcooking keeping it tender.
• 05
  Add the onion and mushrooms the pan and cook until beginning to brown, 6 to 8 minutes.
• 06
  Stir in the tomato paste and flour; cook for about 1 minute. Whisk in beef stock, brandy, soy sauce, mustard, and 1/4 teaspoon of black pepper and bring to a simmer, scraping up any browned bits.
• 07
  Add noodles and bring to boil. Cover, reduce heat to medium-low, and simmer, stirring occasionally, until the egg noodles are tender and sauce is thickened, 8 to 10 minutes.
• 08
  Meanwhile, slice steaks against the grain into 1/4 inch thick slices. Add the meat and any accumulated juices to the skillet with the noodles and cover until warmed through, about 1 minute.
• 09
  Remove from the heat; stir in sour cream and chives, taste and adjust seasoning black pepper as desired. Garnish with chives, thinly slice green onions/scallions and serve.