To char the aubergines, use a barbecue, grill on its highest setting, or cook directly on the hob. Prick the aubergines all over with a fork and grill until charred. This will take about 10 mins over an open flame or 20 mins under the grill – remember to turn them halfway. Remove and put in a sieve to drain any excess water for 10 mins.
Heat oven to 220C/200C fan/gas 7. Use scissors to cut through the seam of the pittas, gently separate the two pieces and cut into triangles. Spread out on a large baking tray, or two smaller ones. Drizzle the oil over, and sprinkle with salt, the spices and seeds. Bake for 10-12 mins until golden, swapping the trays halfway through. Remove and leave to cool. Will keep for up to two days in an airtight container.
Put the aubergine flesh in a food processor or blender, adding two to three pieces of the charred skin too. Add the garlic to the aubergines along with the lemon, mint, coriander, cumin, oil, yogurt and some seasoning. Blend until smooth, scrape into a serving dish, cover and chill in the fridge. Will keep for two days. Just before serving, sprinkle with the chilli flakes.