1. Preheat the oven to 180ºC, drain the chickpeas in a large bowl and roughly mash with a potato masher - you don't want a puree but lumps here and there.
2. Peel and grate the sweet potato and carrot and finely chop the onion, add to the bowl with all other ingredients and mix everything together.
3. Line a baking tray with grease proof paper, rubbing a little oil on it. Take a handful of the mixture, about the size of a clementine, roll in hands until it forms a ball and then flatten down to about an inch thick. (It doesn’t matter if there are small protruding pieces - these will become nice and crispy as they cook)
4. Pop them in the refrigerator to firm up for a while, or just bake them directly in the oven for around 25 minutes.