Begin by preparing your ingredients: thinly slice the large onion, and slice the mushrooms. For the scotch fillet, flatten it to about 3/4cm thick, then slice it into 5mm strips. Season the beef generously with salt and freshly ground black pepper. This initial prep ensures everything is ready once cooking begins, making the process smoother.

Heat half of the vegetable oil in a large skillet over high heat. Sear half of the seasoned beef strips for about 30 seconds per side until nicely browned, then remove to a plate. Repeat with the remaining beef and the second tablespoon of oil, ensuring not to overcrowd the pan, which helps achieve a good sear. I always sear in batches to prevent the meat from steaming instead of browning, which is key for flavor. Once all beef is seared, reduce the heat to medium-high, add the butter to the skillet, and cook the sliced onions for 1 minute. Then add the sliced mushrooms and continue cooking until they are golden brown, about 5-7 minutes.

Sprinkle the flour over the sautéed onions and mushrooms, stirring continuously for 1 minute to cook out the raw flour taste. Gradually add the beef broth in two parts, stirring well after each addition to create a smooth sauce without lumps. Bring the sauce to a gentle simmer, allowing it to thicken over 3-5 minutes. While the sauce simmers, ensure your sour cream is at room temperature to prevent curdling, then stir in the sour cream and Dijon mustard.

While the sauce is cooking, prepare your pasta according to package directions; egg noodles are my go-to for stroganoff. Once the sauce has thickened and the pasta is nearly done, return the seared beef strips along with any accumulated plate juices to the sauce. Simmer for just 1 minute more to heat the beef through without overcooking it, then remove the skillet from the heat. Taste and adjust seasoning with salt and pepper as needed.

Serve the classic beef stroganoff generously over the hot cooked pasta or noodles. Garnish with fresh chopped chives for a bright, aromatic finish. I find the fresh chives truly elevate the dish, adding a lovely pop of color and herbaceousness.