First, make the labneh. Mix the yogurt with a pinch of salt. Line a sieve with muslin, a clean J-cloth or a few sheets of kitchen paper and rest over a deep bowl. Spoon in the yogurt, then cover and put in the fridge to strain for about 4 hrs. You’ll be left with a firmer, soft cheese-like substance – this is your labneh.
Meanwhile, heat the oven to 200C/180C fan/gas 6. Toss the beetroots in the olive oil with salt, pepper and the thyme leaves. Wrap each beet loosely in foil, then place in a roasting tin. Roast for 1 hr, or until tender. Remove from the oven and allow to cool. Peel off the skins, then slice into wedges. Dress with olive oil and season.
Meanwhile, heat the grill to high. Toss the green pepper and chilli with a little oil on a baking tray and grill, turning halfway, until blackened all over (about 10-12 mins). Transfer to a bowl, cover with cling film and leave to cool. Remove and discard the skin and any seeds, then set aside.
To make the sauce, put the pumpkin seeds, most of the herbs and hazelnuts (reserving a few to serve), coriander seeds and cumin seeds in the bowl of a food processor with the garlic and preserved lemon and blitz to coarse crumbs. Add the green pepper, chilli and 1 tsp flaky sea salt. Blitz again to a coarse paste, then add the honey, bread and olive oil. Whizz gradually, adding 100-150ml water, until you have a spoonable sauce. Pour into a bowl, season and add the lemon juice 2 tsp at a time, until it’s balanced and not too sharp.
Smooth a spoonful of labneh on each plate and top with the dressed beets. Spoon over the sauce, then scatter over the remaining hazelnuts and the herbs and drizzle over some more oil.