Heat the oil in a large pan and fry the onions over a low heat for 10 mins until starting to brown. Add 3 tsp of the cumin, the ginger, garlic and curry powder. Stir for a minute to keep the spices from burning.
Tip in the chickpeas and the liquid from the can, along with the tomato purée, 20g of the coriander and some seasoning. Simmer over a low heat for about 10 mins. Add a splash of water if it looks too dry.
Meanwhile, rinse and drain the rice, add the remaining 1 tsp cumin seeds, 2 litres of boiling water and seasoning. Cook for about 10 mins, or until the rice is tender. Drain.
For the raita, grate the cucumber and stir it into the yogurt with the cumin, mint and the remaining coriander. Season, scatter over the pomegranate seeds, then serve alongside the chole and rice.