1. Mix the chickpea flour and spices in a large mixing bowl. Mix the yoghurt and water in a measuring jug, then stir into the flour. Mix gradually until the batter has the texture of wet sand. Don’t worry if it seems too dry while you’re mixing – just keep going, it must be that thick. Set the batter aside and get the vegetables ready.
2. Mix the sweet potato, potato, cauliflower and onion. If you have a scale, weigh your vegetables – you need about 300g.