Soak washed chickpeas overnight in a bowl of cold water, drain and rinse very well.
Cook the onion in ghee and a pinch of salt until soft in a large pan.
Stir in celery, carrots and garlic, and cook for a few minutes.
Add spices, tomatoes, tomato paste, maple syrup, chickpeas, lentils and stock, bring to a simmer, partially cover the pot and cook gently for 1 hour, stirring occasionally. Add more water or stock if needed.
Check that the chickpeas are tender, if not simmer the soup until they are soft.
Add the spinach and lemon juice, and cook just for another 3 minutes.
Season well with salt and pepper, mix through the herbs, and serve each bowl drizzled with a little olive oil and accompanied by a wedge of lemon.