Barbecued butterflied leg of lamb with tzatziki

The thought of lamb on the barbecue with garlic and rosemary makes my mouth water! As a young commis chef, I worked with a Greek chef who showed me how his Mum made tzatziki. The secret, he told me, was to leave the cucumber to steep in the vinegar overnight. Apologies to my Greek friend, but the tzatziki is so good with this barbecued lamb that I just had to give your secret away. On the side I usually serve barbecued veg – aubergine, courgette, red onion and red pepper – which I cook on the barbecue before the lamb and marinate in a herby dressing while the meat is cooking.

INGREDIENTS
3kg leg of lamb, boned and butterflied, skin scored (ask your butcher to do this)
sea salt
freshly ground black pepper

FOR THE MARINADE
5 garlic cloves, peeled and crushed
6 tablespoon olive oil
5 tablespoon chopped rosemary
2 red chillies, sliced
2 tablespoon clear honey

FOR THE TZATZIKI
4 medium (or 3 large) cucumbers
7 tablespoon white wine vinegar
700g greek-style natural yoghurt
4 garlic cloves, peeled and finely chopped
a handful mint leaves, finely sliced
A splash extra virgin olive oil

METHOD
For the marinade, mix the garlic, olive oil, rosemary, chillies and honey together in a bowl and season well with salt and pepper. Lay the lamb in a roasting tray and pour the marinade over, rubbing it into the lamb. Cover with cling film and leave to marinate in the fridge for at least 3 hours, or overnight for best results.
To make the tzatziki, peel, halve and deseed the cucumbers, then grate into a bowl and add the wine vinegar and a pinch of salt. Cover and leave overnight in the fridge, alongside the lamb.
The next day, drain the cucumber and squeeze in your hands to remove all excess juice, then place in a clean bowl. Add the yoghurt, garlic, mint and olive oil and mix well. Season with salt and pepper to taste, cover and refrigerate until ready to serve.
Light your barbecue around 30 minutes before you are planning to start cooking.
When the coals are ready, carefully lift the lamb from the marinade and place it on the barbecue. If the coals start to flame up, pull the lamb to the cooler side until they die down. Cook the lamb for 25 minutes, turning every 2 or 3 minutes.
When the lamb is done, transfer it to a tray, cover with foil and leave to rest for 10 minutes. Get everything else ready in the meantime. Put the meat back on the barbecue for a few minutes to warm up, then slice on a board and place on a warmed platter. Serve at once, with the tzatziki on the side and barbecued veg or salads.