Saute the onion in a large pan until translucent. Add the ginger, garlic and chilli, stir for a minute before adding the spices. Cook for a few minutes.
Add the tinned tomatoes, bring to the boil then reduce the heat and simmer for around 15 minutes to form a thick gravy.
Add the cauliflower and cook for 4 minutes before adding the chickpeas. Heat through and add the spinach, stirring constantly until wilted. Either serve as soon as wilted, or cook for a few more minutes to evaporate some of the water as it is released. from the spinach.
Mix together the ingredients for the yogurt sauce in a small bowl. Serve with the curry.