Photo: Tara Fisher
Liberally sprinkle polenta into an oiled 20 x 20cm deep tin to coat the base. Sift the chickpea flour into a bowl. Gradually whisk in 450ml water.
In a large pan, heat the oil over a moderate heat. Fry the cumin seeds briefly, then add the turmeric, ginger, chilli, coriander and seasoning. Stir for a further minute.
Whisk the chickpea flour mixture, then pour into the pan, stirring. Simmer gently for 5 minutes, stirring continuously. Once the mixture is thick and coming away from the side of the pan, use a spatula to scrape the mixture into the oiled tin. Quickly wet your hands in a bowl of cold water and flatten the batter out evenly, dipping your hands in and out of the water as needed, until the surface is level. Sprinkle a little more polenta on top, then gently press it in and set aside to cool.
Mix the tahini paste and lemon juice together with enough water to make a thick dip, then season. Cut the cold chickpea mixture into 24 chips and carefully roll each in a little more polenta. Gently shallow fry in batches in oil until crisp and pale golden. Drain on kitchen paper and serve immediately with the tahini lemon dip.