In a small bowl, mix together garlic, saffron, paprika, cumin, cinnamon, turmeric and cayenne; set aside.

Heat oil in a large Dutch oven or skillet over medium heat, and brown lamb on all sides, working in batchs if needed.

Remove lamb and let cool slightly then rub with spice mixture. Let stand for at least one hour.

Return lamb back to the pan and add salt and pepper, onion, cilantro and preserved lemon (if using).

Add 2 1/2 cups water and bring to a boil over high heat.

Reduce heat and simmer, covered tightly for 1 hour, turning lamb occasionally to evenly baste.

Continue cooking, adding more water if necessary, until lamb is fork tender, another 45 minutes to an hour.

Remove lamb to serving platter and cover.

Increase heat and reduce sauce until thick, then serve alongside lamb.