For the labneh, suspend a sieve lined with muslin cloth or a thin, clean tea towel over a bowl. Mix together the yogurt, lemon juice and ½ tsp of salt, then transfer to the lined sieve. Leave to strain in the fridge for 12 hours (or up to 24 hours). Discard the liquid, transfer the labneh to a bowl and top with half the sumac and 1 tbsp extra virgin olive oil.
Coat the aubergines with the remaining sumac, the cumin and olive oil. Season and marinate for 30 minutes.
Meanwhile, cook the pearl barley according to pack instructions. Drain well, tip into a bowl and stir in the lemon zest, garlic, spring onions, pomegranate seeds and dates.
Whisk the remaining extra virgin olive oil, the vinegar, pomegranate molasses and honey together. Drizzle over the salad.
Preheat the grill to high or set a large griddle pan over a high heat. Cook the aubergine, cut-side down, for 10-12 minutes, or until lightly charred and tender.
Tip the pearl barley salad onto a large platter. Top with the aubergine and serve with the labneh and watercress or rocket.