Heat oven to 180C/160C fan/gas 4. Put the walnuts in a roasting tin and the pitta strips in another. Drizzle a little oil over the pitta strips and season with the za’atar and some salt and pepper. Place both trays in the oven and roast for 10 mins, then remove the walnuts. Roast the pitta strips for a further 3-5 mins until golden and crisp. Remove from the oven.
Meanwhile, prick the aubergines and peppers all over with a fork. If you have a gas hob, turn on the rings to medium high (or better still, light the barbecue and move the coals to one side). Place the aubergines over the heat until they start to collapse, then turn them using tongs and cook the other side. Continue rotating until charred all over and soft all the way through. Repeat with the red peppers until charred and softened. If you don’t have a gas cooker or a barbecue, heat your grill to high (about 275C) and spread the pricked aubergines and peppers on a foil-lined baking tray, coating with a little oil. Grill for 10-15 mins on each side until charred and softened. Set aside.
Remove the aubergines and peppers from the heat and allow to cool, then transfer to a chopping board. Carefully peel the skin from the peppers, halve and scoop out the seeds. Halve the aubergines and scrape the tender flesh into a bowl. Don’t worry if a little of the charred skin escapes into the bowl, it will add more flavour – but try to make sure there aren’t big shards of it in there.
Tear the pepper into strips and put it in the bowl with the aubergine. Add almost all the chopped parsley, season, and stir in the olive oil and the vinegar. Arrange on a platter and crumble the walnuts and feta over the top. Garnish with some extra parsley and mint leaves.