In a large pot or tagine, heat olive oil over medium-high heat. Season the lamb shanks with salt and pepper, then sear them on all sides until browned. Remove and set aside.

Sauté Vegetables

In the same pot, add chopped onion and minced garlic. Sauté until the onion is translucent. Add diced zucchini and carrots, cooking for another 5 minutes.

Add Spices and Liquids

Stir in the cinnamon stick, cumin seeds, coriander seeds, canned tomatoes, and chicken broth. Return the lamb shanks to the pot. Bring to a boil, then reduce to a simmer.

Braising

Cover the pot and let the lamb shank braise for about 2 to 2.5 hours, or until the meat is tender and falling off the bone.

Prepare the Couscous

In a separate pot, bring 1 cup of water to a boil. Add couscous and a pinch of salt, remove from heat, cover, and let sit for 5 minutes. Fluff with a fork and mix in chopped cilantro and lemon juice.