• Melt 1 tablespoon of the butter in a large, deep skillet over medium-high heat. Add the mushrooms and cook for 5–7 minutes, stirring occasionally, until they are browned and the liquid they release has evaporated. Transfer the mushrooms to a plate and set aside.

  Add the ground beef and diced onion to the same skillet. Cook for 7–8 minutes, breaking the beef into crumbles, until the meat is browned and the onion is tender. Drain off any excessive grease, leaving a light coating in the skillet.

  Reduce the heat to medium. Add the remaining 2 tablespoons butter and the garlic. Cook for about 30 seconds, just until the garlic is fragrant.

  Sprinkle the flour evenly over the beef. Cook for 1–2 minutes, stirring continuously, so the flour coats the meat and loses its raw taste.

  Gradually pour in the beef stock while stirring and scraping up the browned bits from the bottom of the skillet. Stir in the Worcestershire sauce, Dijon mustard, paprika, salt, and pepper. Bring the liquid to a gentle boil.

  Add the dried egg noodles and stir to distribute them evenly. Reduce the heat to maintain a steady simmer, cover, and cook for about 10 minutes, stirring every 2–3 minutes so the noodles cook evenly and do not stick to the bottom of the skillet.

  If the noodles absorb the stock before they are tender, add additional stock a little at a time. The mixture should remain loose enough for the noodles to move through the sauce.

  Once the noodles are tender, return the browned mushrooms to the skillet and stir to combine. Remove the skillet from the heat and allow it to cool for about 1 minute.

  Stir in the sour cream until completely incorporated. Taste and adjust the salt and pepper as needed. Let the stroganoff rest for 2–3 minutes before serving; the sauce will continue to thicken as it stands.

Notes

• For fresh homemade egg noodles, begin with 2½ cups beef stock instead of 4 cups. Add the fresh noodles to the simmering sauce and cook uncovered for 3–5 minutes, depending on their thickness. Keep another ½ cup of stock nearby and add it a little at a time if the sauce becomes too thick before the noodles are tender.

  Sour cream can separate if it is added while the sauce is boiling. Remove the skillet from the heat and let it cool briefly before stirring it in.

  The mushrooms are cooked separately and returned near the end so they remain browned and do not become overly soft while the noodles cook.