Chicken Tagine with preserved lemons and olives (Morocco)

A lovely Moroccon main course, great with couscous and flat bread. (Those recipes to follow). Ingredients: 1/2 tsp saffron, crushed 250 ml hot chicken stock 3 onions, chopped 2-3 tbsp olive oil 1 tsp ground ginger 1 tsp ground cumin 3 cloves garlic, sliced thinly 1 chicken, jointed or 7 chicken thighs/legs mixed 1 tsp black peppercorns, crushed 6 small preserved lemons, quartered (or 2 large ones, chopped) 100 g mixed olives 1 handfuls cor