Step 1

Heat the vegetable oil in a large pan and add the onion, celery and a pinch of salt. Put on a lid and cook gently for 10 minutes, stirring regularly. Add the garlic, preserved lemons and red chillies, and cook for 2 minutes. Add the tomato purée and spices, and cook for a further 2 minutes before adding the chopped tomatoes, potato, chickpeas and 1.25 litres of boiling water.

Step 2

Bring to the boil, then turn down and simmer for 30 minutes until the potatoes are tender. Tip in the spinach, flat-leaf parsley and a little seasoning, and stir for 1 minute until wilted. Add the lemon juice, then spoon into bowls with lemon wedges for squeezing.