Mix together the marinade ingredients except the yoghurt in a pestle and mortar to form a paste. Add the paste to the yogurt and rub well all over the lamb necks. Cover and refrigerate for 24 hours.
Bring the lamb up to room temperature for an hour or so before cooking then preheat a cast iron pan in Roccbox.
Drizzle a little oil over the lamb necks and pop them into the hot pan to cook for 6-7 minutes, turning and rotating as required.
Transfer to a plate or board to rest for 5 minutes.
Place the broccoli into a cast iron tray, drizzle with a little olive oil and sprinkle over the garam masala. Season and cook in Roccbox for 3 minutes.
Allow the broccoli to sit in its tray whilst you carve the lamb, rip over some fresh mint and coriander and serve with some steamed rice or flatbreads.