Tip the lamb into a bowl; add the yoghurt, fenugreek, 3 of the crushed garlic cloves, a grind of pepper and some salt. Mix together, then cover and marinate in the fridge for 24 hrs ideally, or at least 2 hrs.
Thread the marinated lamb and the slivers of onion onto 5-6 metal skewers. Set aside.
Thread the pepper and aubergine onto 5-6 metal skewers; drizzle with the olive oil. Season well; set aside.
Either light a BBQ or heat a grill to med high.
Meanwhile, make the chilli mint oil by mixing the extra virgin olive oil, mint, chillies and remaining crushed garlic together in a bowl. Set aside at room temperature until needed.
Put the vegetable skewers on a foil lined baking tray and the lamb skewers on another. Grill the vegetables for 10 minutes until just catching, keep warm and repeat with the lamb for 10-12 mins.
You can put the skewers directly over the hot embers of a BBQ and lightly char all over for 8-10 mins. (lovely for a summer bbq)
Serve the veg and meat skewers on a big plate and spoon the chilli mint oil on top to eat all together. Lovely with warm pitta or crusty bread.