Neil Perry's snapper with spiced sweet potato and yoghurt

• 4 snapper fillets, about 200g each, skin on

• sea salt

• 2 tbsp olive oil

• 1 cup Greek-style yoghurt

• squeeze of lemon, plus cheeks to serve

• freshly ground white pepper

Sweet potato salad

• 500g sweet potato, peeled and cut into 2cm pieces

• 125ml extra virgin olive oil 1 large onion, roughly chopped

• ½ tsp ground ginger

• ½ tsp ground cumin

• ½ tsp paprika

• ½ tsp chilli powder

• juice of ½ lemon

• 12 green olives, pitted and roughly chopped

• ¼ cup flat-leaf parsley leaves