Method

Preheat the oven to 200°C. Season the meat really generously all over with salt and pepper. This is important, as the sea salt combined with a high heat will give the beef a deliciously textural, crunchy outer coating.

Place a heavy-based frying pan, large enough to hold the whole fillet, over a high heat. When the pan begins to smoke, add the oil and swirl the pan to coat the base well. Add the meat and brown really well all over; this is best achieved by leaving the meat alone – if you push it around in the pan it will stew rather than form a crust. Once the meat is really well browned, transfer it to a roasting tray and place on the middle shelf of the oven to finish cooking for 5 minutes.

Meanwhile, place the butter in a heavy-based nonstick pan over a high heat and allow it to melt and begin to foam. As soon as the butter begins to colour (and smell deliciously nutty), add the anchovies and stir vigorously until they disintegrate and become a part of the sauce.

When the meat is cooked, remove it from the oven and set aside in a warm place to rest while you wilt the greens.

Once the anchovies have melted into the sauce and thickened it slightly, add the wine vinegar. Now add the greens and cook briefly, stirring, to just wilt the vegetables. Set aside

To serve, cut the meat into thick slices, allowing 3 slices per person. Arrange on warm plates and spoon the sauce and wilted greens over the top. Serve at once.