Roast chicken with pistachios and sour cherries

Ingredients

• 1 red onion, cut into 1cm slices
• 100g greek yogurt
• 1 tsp orange blossom water or rosewater
• 2 pinches saffron, soaked in 1 tbsp warm water
• ¼ tsp ground nutmeg
• ½ tsp ground cinnamon
• ½ tsp ground cardamom
• 2 garlic cloves, roughly chopped
• 1 tsp salt
• 1.5kg whole free-range chicken, spatchcocked
• 60g shelled pistachios, whizzed to a coarse powder
• 50g dried sour cherries, roughly chopped (or barberries)
• 1 tsp sumac
• Small bunch mint, leaves picked and roughly chopped