Place the lamb chunks, diced onion, and minced garlic into the slow cooker. Sprinkle the cumin, cinnamon, ginger, paprika, salt, and black pepper over the top and stir to coat the meat evenly.
Add the diced tomatoes, chopped apricots, chickpeas, and chicken broth. Stir everything together until the ingredients are well combined.
Cover and cook on low for 7 to 8 hours or on high for 4 hours until the lamb is tender and pulls apart easily with a fork.
About 10 minutes before serving, bring the water to a boil in a small saucepan. Stir in the couscous, cover, and remove from heat. Let it sit for 5 minutes, then fluff with a fork.
Spoon the couscous into bowls and top with the lamb tagine. Finish with chopped cilantro and a squeeze of lemon.