Heat the oil in a large pan over a medium heat. Add the chopped onion and cook for 5 minutes until softened.
Stir in the crushed garlic, cumin, coriander and chilli flakes. Cook for 1 minute until the spices are fragrant.
Add the drained chickpeas, chopped tomatoes and vegetable stock. Bring to a simmer and cook for 10 minutes.
Stir in the frozen spinach and cook for a further 5 minutes until the spinach has thawed and heated through.
Season with salt, black pepper and the lemon juice. Stir well and taste, adding more seasoning if needed.
Serve hot on its own or with rice, couscous or crusty bread.