Prepare the ingredients

1. If the beef is unevenly thick, place it between two sheets of baking paper and gently flatten it with a meat mallet or rolling pin. Do not pound it too thin.

2. Cut the beef across the grain into thin, even strips, approximately 2.5 × 5 cm. Pat the strips dry with kitchen paper so they brown properly.

3. Wipe the mushrooms clean and cut them into fairly thick slices. Finely dice the onion, mince the garlic and prepare the beef stock.

Sear the beef

4. Heat a large frying pan or cast-iron skillet over high heat. Add a small amount of olive oil and allow the pan to become properly hot.

5. Arrange part of the beef in a single layer. Sear for approximately 60–90 seconds on each side, until browned but not fully cooked through.

6. Transfer the seared beef to a plate. Repeat with the remaining strips, adding a little more oil when necessary. Do not overcrowd the pan, or the beef will release liquid and steam.

Cook the vegetables

7. Reduce the heat to medium. Add the butter and a little remaining olive oil if the pan looks dry.

8. Add the onion and cook for 3–4 minutes, stirring occasionally, until soft and lightly golden.

9. Add the sliced mushrooms. Cook uncovered for 5–6 minutes, until their released liquid has evaporated and the edges begin to brown.

10. Stir in the minced garlic and cook for about 30 seconds, just until fragrant.

Prepare the Stroganoff sauce

11. Add the tomato paste, Dijon mustard and sweet paprika. Stir over medium heat for one minute to cook the tomato paste and release the paprika’s flavour.

12. Sprinkle the flour evenly over the mushrooms and stir until no dry flour remains. Gradually pour in the beef stock while scraping the browned pieces from the bottom of the pan.

13. Simmer the sauce gently for 2–3 minutes, stirring regularly, until it begins to thicken. Lower the heat and stir in the double cream until the sauce is smooth.

Finish and serve

14. Return the beef and any juices collected on the plate to the pan. Toss gently in the sauce for 1–2 minutes, only until the meat is warmed through. Do not let the sauce boil vigorously.

15. Taste and adjust with salt and freshly ground black pepper. If the sauce is too thick, add a small splash of stock; if it is too thin, simmer it briefly before serving.

16. Remove from the heat, sprinkle with chopped parsley and serve immediately over egg noodles, ribbon pasta, rice or mashed potatoes.