Try Gordon's delicious recipe, featuring flavours of sherry, mustard and rosemary, for yourself.
Preheat the oven to 200ºC/Gas 6.
Place a heavy-based ovenproof frying pan over a medium heat and add a dash of olive oil. Season the beef all over, then brown in the pan on all sides for a minute or two. Add the garlic, thyme and rosemary and roll the beef around with the herbs. Add a couple of knobs of butter and, when melted, baste the beef in it. Transfer the pan to the oven and roast for 10–12 minutes (rare) or 15–17 (medium rare).
Meanwhile, make the salsa verde. Put the anchovies with a teaspoon of their oil, capers, garlic, a pinch of salt and the half the herbs, in a mortar and pound with a pestle until a paste has formed. Stir in the mustard and vinegar. Loosen with a little oil, then stir in the rest of the herbs. Mix well to your preferred consistency. Taste and adjust the seasoning as necessary.
Once the beef is cooked to your liking, baste it in the pan juices and transfer to a warm plate. Spoon over a couple of spoonfuls of salsa verde, cover loosely with foil and leave to rest for 10 minutes.
To serve, slice thickly and spoon the salsa verde alongside.