Anchovy-Rosemary Butterflied Lamb with Red Wine Jus

Method

1. Finely chop or pound the anchovies, garlic and rosemary leaves and mix with the lemon zest, half the olive oil and the pepper to a paste. Make shallow cuts in the thickest parts of the lamb so it is an even thickness, rub the paste over both sides, cover and refrigerate for 4 h. The anchovy melts away, leaving deep savouriness rather than fishiness.

   Add in this stepButterflied lamb leg (about 4 cm thick) 500 gAnchovy fillets in oil 2Garlic cloves 3Rosemary sprigs 2Lemon (finely grated zest only) ½Extra virgin olive oil ¾ tbspBlack pepper ½ tsp

2. Take the lamb out 30 minutes before cooking and preheat the oven to 200 °C for 15 min. Sprinkle the salt evenly over the lamb just before cooking; the anchovies are already salty, so don't add more than the recipe says.

   Add in this stepFlaky salt ½ tsp

   oven

3. Peel the potatoes, cut into 4–5 cm chunks and put them in cold salted water. Bring to the boil on high heat and cook for 9 min once boiling. Drain, let them steam dry for 2 minutes, then shake the pot to rough up the surfaces.

   Add in this stepFloury potatoes 400 gFlaky salt ¼ tsp

   high heat

4. Put the duck fat in a 25×20 cm roasting tray and heat it in the oven for 5 minutes until shimmering. Carefully add the potatoes (the fat spits), turn to coat, sprinkle with salt and roast for 45 min, turning every 15 minutes, until glassy-crisp and deep golden all over.

   Add in this stepDuck fat 2 tbspFlaky salt ¼ tsp

5. Heat the rest of the olive oil in a 24 cm ovenproof cast-iron pan on medium-high heat and sear the lamb for 5 min in total, both sides, until a dark brown crust forms. Move the pan to the oven for 18 min, until the thickest part reads 55 °C (medium-rare). The handle stays hot long after it leaves the oven, so wrap it in a cloth as a reminder.

   Add in this stepExtra virgin olive oil ¾ tbsp

   medium-high heat

6. Transfer the lamb to a board, cover loosely with foil and rest for 12 min. The centre climbs to 57–58 °C and the juices stay in the meat when you slice.

7. Jus: pour off all but 1 tbsp of fat from the pan, set it on medium heat and cook the chopped shallots and thyme for 2 min. Pour in the wine, scrape up the browned bits and reduce by half, then add the stock and the resting juices from the board and simmer for 6 min until it coats the back of a spoon. Take off the heat, swirl in the cold butter until glossy and remove the thyme.

   Add in this stepShallots 1Thyme sprigs 2Dry red wine 100 mlBeef stock 200 mlCold butter 15 g

   medium heat

8. Slice the lamb 1 cm thick across the grain, fan it out on plates with the duck-fat potatoes and spoon the jus over the meat.