Trim any excess fat from the lamb leg and cut the meat into 1-inch cubes.
In a small bowl, combine the ground cumin, coriander, cinnamon, turmeric, sea salt, and black pepper.
Toss the lamb cubes in the spice mixture until every piece is evenly coated.
Heat the olive oil in a heavy-bottomed pot or tagine over medium-high heat.
Sear the lamb cubes until they are browned on all sides, then remove them from the pot and set aside.
Add the diced onion, minced garlic, and grated ginger to the same pot, sautéing until softened and fragrant.
Return the lamb to the pot and add the chopped dried apricots and beef broth.
Bring the liquid to a gentle boil, then reduce the heat to low, cover with a tight-fitting lid, and simmer for 45 to 60 minutes until the lamb is tender.
Stir in the fresh spinach just before serving, allowing it to wilt into the sauce for one minute.