Heat the olive oil in a pan and add the chickpeas and spices. Fry, stirring occasionally until fragrant and the chickpeas are coated in the spices.
While they are cooking, combine all the ingredients for the dressing (except the sumac) in a small bowl and mix well.
Remove the chickpeas from the heat and set aside while you put together the salad. Wash the baby spinach leaves and dry as much as you can. Place in a large serving bowl and sprinkle the chopped tomatoes over the top. Add the chickpeas and drizzle with the dressing. Sprinkle liberally with sumac. Toss just before serving.