Auntie Caroline's preserved lemons go particularly well in this dish - there's no sharpness just oodles of flavour. You'll find that the longer and more slowly you cook the chicken the better. It will be beautifully soft to eat.
Heat the oil and fry the onions until softened in a heavy based casserole or similar.
Grate the fresh ginger. Add it to the onions with the cumin and garlic and cook until softened. Set mixture aside
Add the chicken thighs to the pot and cook until lightly browned
Put the onion mixture back in the pot add the courgette or squash. Add the chopped lemons and saffron. Mix well.
Add the water and cook on a low heat for at least an hour until the chicken is very soft. Check half way through and add more water if the mixture is getting dry.
Add the olives and heat through for 5 to 10 minutes. Check seasoning and add salt if necessary. Sprinkle with chopped coriander.