First of all, you need to preheat your oven, but the temperature will depend on how long you want to cook the stew for. If you want it ready in 3 hours, preheat it to 180ºC/350ºF/gas 4, but if you want to cook it for 6 hours, then you need the oven on at 140ºC/275ºF/gas 1.
Put a large casserole-type pan on the hob on a high heat and add a couple of good lugs of olive oil. Let this heat up, then add your potatoes, onions, carrots, celery, rosemary, cumin, paprika, and orange zest and juice, and stir together. Cook for 1 minute, then mix around again before adding the meat, the chickpeas and the tomatoes. Season lightly with salt and pepper and pour over enough water to cover everything. Bring to the boil and put into the oven. You are now free to go out for a few hours (for the whole day if you want to!). Serve the stew in bowls with a dollop of yoghurt and a sprinkle of coriander leaves.