Heat the oil in a large frying pan, add the chicken and onions and fry, in batches if necessary, for 5 minutes until golden.
Stir in the garlic, then mix in the flour. Add the stock, lemon rind and juice, saffron, cinnamon and plenty of seasoning and bring to the boil.
Preheat the oven to 180°C (350°F), Gas Mark 4.
Transfer to a tagine or casserole dish. Add the chickpeas and potatoes, mix together, then cover and cook for 2 hours.
Stir, then sprinkle with the herbs. Spoon into shallow bowls and serve with warm pitta breads.