Heat the olive oil in a large, heavy-based ovenproof dish and brown the onions for 3 minutes.
Add the chicken pieces to the pan and season with the turmeric, saffron, ginger, pepper and salt to taste. Stir in 300 ml (10 fl oz) of the water, cover the pan, and leave to simmer over a low heat for around 10 minutes.
Stir in the remaining water, the herbs, cumin and paprika. Allow to reduce for around 10 minutes until the sauce has thickened. Add the olives and the lemon juice, and simmer for a further 5 minutes.
Meanwhile, rinse the preserved lemons, cut them in half, and remove the pulp. Cut the rind into strips.
Transfer the chicken to a serving platter, pour the sauce around it, and garnish with the strips of preserved lemon.