In a tagine pot, a round-bottomed wok or Dutch oven with lid, heat the olive oil, then add the onions and sauté over low heat, stirring constantly until they are translucent, silky, and soft, then add the garlic, saffron (or turmeric) and ginger.
Add the chicken pieces, positioning them so that they are all lying flat (not layered on top of eachother), then season with salt and pepper, add just enough water to cover the pieces, and put the lid on to allow the chicken to simmer slowly on low heat.
Check the chicken periodically, turning the pieces over at around 15 minutes, then at 30 minutes or so, remove the lid to check if the chicken is ready – it should be moist, tender and practically falling off the bone.
Add the preserved lemon quarters and brine, fresh coriander and olives, then simmer for another 10-15 minutes without the lid to further reduce the sauce.
Serve in the tagine pot or if you used a wok or Dutch oven, transfer to a serving dish, and garnish with more fresh coriander. Serve with Moroccan bread or plain couscous.