Preheat the oven to 200C (180C fan, gas mark 6).
Put the spring onions, tomatoes, tomato purée and mixed herbs into a saucepan over a medium heat. Cook for 5 to 8 minutes, stirring often, until reduced and thickened.
Arrange the naan on a baking sheet, divide the tomato mixture between them equally. Add the chicken, then sprinkle over the cheese. Bake for 5 to 6 minutes.
Meanwhile, mix together the salad ingredients, and serve with the naan once ready.