Cook the onion and garlic in 2cm or 1 inch of water for five minutes until soft. If the water evaporates too quickly, just add a little more.
Add the red pepper and cumin seeds. Stir and cook for a further 2 minutes.
Add the passata and stock, bring to the boil then turn down and simmer for 10 minutes.
Add the chickpeas, vinegar and cook for a further five minutes.
Add the spinach and season to taste with freshly ground black pepper. Cook until the spinach begins to wilt, then serve into warm soup bowls.