Heat the oil in a large pot and add the onion, fry for a couple of minutes then add the cumin seeds and fry for a couple of minutes more.
Add the coriander, turmeric, garlic, curry powder, ginger and cayenne and stir to coat, cook until fragrant, about a minute. Season with salt and pepper.
Pour in the tomatoes and bring to a boil, simmer over a medium heat for about 6 minutes then add the chickpeas and frozen spinach and simmer for another 4-5 minutes until the spinach is defrosted into the sauce.
Add the lemon juice and serve with rice or naan (or both!) and topped with fresh coriander.
Nutrition information is an estimate and will vary depending on the exact ingredients used.