Drain and rinse the chickpeas, place in a medium saucepan on a medium heat, cover with fresh water and cook on a very gentle simmer for 45 minutes to 1 hour, until the chickpeas are completely soft. Drain, transfer to a large mixing bowl and leave somewhere warm. Place the coriander, mustard and cumin seeds in a large saute pan and dry-roast them until they begin to pop. Use a spice grinder or pestle and mortar to crush them to a powder and then add to them the curry powder, turmeric, sugar and ½ teaspoon of salt; set aside. In the same pan, heat up half the oil and cook the onion for 5 minutes on a high heat, stirring occasionally, so that it starts to gain some colour. Add the spice mix and keep cooking on a medium heat for another 5 minutes, until the onion is completely soft. Transfer to the bowl with the warm chickpeas and keep aside. Bring a large pot of water to the boil, throw in the cauliflower and blanch for just 1 minute. Drain, pat dry and set aside. Once the cauliflower is completely dry, heat up the remaining oil in the same pan you cooked the onion in (you don’t need to clean it), add the cauliflower, along with ¼ teaspoon of salt, and fry on a high heat for 3-4 minutes, just to give it colour. Add the hot cauliflower and any oil from the pan to the onion and chickpeas and stir well. Leave for 5 minutes if you want the salad warm or longer for room temperature. Add the mango to the salad, along with the chilli, coriander, lime juice and spinach. Stir well and serve at once or chill and serve within 24 hours.