Preheat your BBQ. Put the aubergines, onion and garlic on the top shelf and gently barbecues them until soft. This should take about 30 minutes. Make sure they don’t burn so keep turning them over. When cooked, put them on a plate and let them cool.
Scoop out the flesh of the aubergine and red onion into a small food processor bowl. Pop the he flesh out of half the garlic bulb - keep the other half for other dishes or salad dressings.
Add the garlic flesh, lemon juice, tahini, oil, cumin and cayenne to the aubergine. Season with salt & pepper. Blitz the mixture until you get a smooth purée.
Transfer it to a serving dish and refrigerate until serving.
Garnish with a pinch of paprika/cayenne and mint leaves just before serving.