Heat the olive oil in a heavy-bottomed pot over medium-high heat and sear the cubed lamb seasoned with sea salt and black pepper until browned on all sides.
Add the diced yellow onion, minced garlic, and sliced carrots to the pot, sautéing for 5 minutes until the vegetables begin to soften.
Stir in the harissa paste, ground cumin, and ground cinnamon, ensuring the lamb and vegetables are thoroughly coated in the aromatic spices.
Pour in the beef broth and add the chopped dried apricots, then bring the mixture to a gentle boil before reducing the heat to low.
Cover the pot and simmer for 20 minutes, adding the diced zucchini during the final 5 minutes of cooking to maintain its texture.
In a separate small saucepan, bring the water to a boil, stir in the couscous, cover, and remove from heat to let it steam for 5 minutes.
Fluff the couscous with a fork and serve the spicy lamb tagine directly over the grains for a complete, flavorful meal.