Preheat the oven to gas 6, 220°C, fan 200°C. Wash the sweet potato and cut into wedges, roughly 1 inch thick. Place a baking sheet on a baking tray and lay the chunks of potato with a drizzle of olive oil. Cook for 40 - 60 minutes, or until the middle part is tender.
Warm the pitta bread, split along one side and open out. Stuff each pitta with a couple of wedges, salad leaves, 50g of salad tomatoes and the chicken.
For extra heat, add a sprinkle of chilli flakes and as an option, add some black olives.