Beef Tagine with Sweet Potatoes, Peas, Ginger and Ras El Hanout

Heat ghee in a tagine or heavy-based casserole dish. Stir in the ginger and onion and saute until soft. Toss in the beef and sear it on all sides, then stir in the ras el hanout. Pour in enough water to just cover the meat mixture and bring it to a boil. Reduce the heat, cover the lid, and cook gently for about 40 minutes. Add the sweet potato to the tagine, season with salt and pepper to taste, cover with the lid and cook gently for a further 20 minutes until the meat is tender. Toss in the peas and tomatoes, cover the lid, and cook for 5-10 minutes. Sprinkle the preserved lemon and the cilantro over the top and serve.