Preheat oven to 325 degrees.
Brown beef in a large oven-proof pot. Remove beef when browned and saute onions in the same pot. Add lemon, garlic, Ras el Hanout, cumin, coriander, and harissa to onions and stir until aromatic. Return browned beef to pot. Add stock, thyme, and salt and pepper to taste.
Cover pot and braise in oven for 2.5 - 3 hours until meat is tender.