Heat one tablespoon of oil in the tagine base on a medium setting. Fry the onion, fennel and garlic until all are just beginning to brown. Transfer to plate.
Add the remaining oil and fry the pieces of lamb until they are evenly browned.
Add all the spices (ginger, cumin, cilantro, cayenne pepper and salt) to meat and stir well, continue to cook for one minute.
Return the onion, fennel and garlic to the Tagine. Add the dates and 3/4 cup of water. Stir well.
Cover and cook very gently, stirring occasionally for 3 - 3 1/2 hours. The spices will thicken the liquid as the dish cooks, so check after 1 1/2 hours and add the remaining water little by little.