Soak a handful of wood chips in water according to the packet instructions. Light the barbecue (see note below for coal set up). Blacken the leeks directly on the coals for 10 to 15 minutes, turning halfway, then remove to a board.

Meanwhile, pick the soft herb leaves into a pestle and mortar with a pinch of sea salt, pound into a coarse paste, then peel and pound in the garlic. Roughly pound in the pistachios, then muddle in 2 tablespoons of extra virgin olive oil, squeeze in the juice of 1 lemon and scrunch in the breadcrumbs until combined (blitz in a food processor, if you prefer).

Lay the lamb out like an open book and massage all over with salt, black pepper and 1 tablespoon of olive oil. Sear on the hot zone for 5 minutes, or until gnarly, turning regularly with tongs, then move to a board, skin side down. Massage the top with the mustard, then pat on the herby crumbs.

Peel off and discard the outer charred layers of the leeks, cut into 2cm lengths and place in a 20cm x 25cm roasting tray. Rub half the sage leaves with olive oil, then add to the tray with the tomatoes and a generous splash of water. Carefully remove the grill and place the tray directly in the cool zone. Replace the grill, then sit the lamb, crumb side up, on the bars over the tray. Halve the remaining lemon and tuck it under the side of the lamb nearest the coals. Drain the wood chips and place on the hot zone with the remaining sage sprigs. Cook lid on, top vent half open above the meat for 30 minutes.

Carefully lift up the lamb and the grill and pour the beans into the tray, juice and all. Replace the grill and lamb and cook for a further 10 to 15 minutes with the lid on, top vent half open, or until the internal temperature reaches 55ºC. Remove the lamb to rest, covered, for 30 minutes (the internal temp should rise to 60ºC), leaving the beans to reduce for another 15 minutes.

Mix 1 tablespoon of red wine vinegar into the beans, season to perfection, then slice and add the lamb. Great with crusty bread and a green salad.

Coal set up

50/50: Simply pile all your coals evenly into one half of the barbecue, leaving the other half clear. This gives you a clear hot zone and cool zone, with a medium area in the middle where you can get the best of both worlds. This set-up is helpful for recipes where you need to sear or get something going over direct heat, but then want to give it time to cook through more gently over indirect heat.