Preheat your oven to 325 F (165 C). Season the lamb shanks generously on all sides with kosher salt and black pepper.
Heat the olive oil in a large heavy-bottomed Dutch oven over medium-high heat. Sear the lamb shanks until golden brown on all sides, about 8 to 10 minutes. Remove the shanks and set them aside on a plate.
Reduce the heat to medium. Add the chopped onions to the pot and sauté until softened, about 5 minutes. Stir in the minced garlic, harissa paste, Moroccan spice blend, and tomato paste. Cook for 2 minutes until fragrant.
Pour in the beef broth, using a wooden spoon to scrape up any browned bits from the bottom of the pot. Return the lamb shanks to the pot along with any resting juices.
Bring the liquid to a gentle simmer. Cover the Dutch oven with a tight-fitting lid and transfer it to the preheated oven. Braise for 2 hours.
Carefully remove the pot from the oven. Stir in the chickpeas and halved dates. Cover and return to the oven for an additional 30 to 45 minutes, or until the lamb is fall-apart tender.
Skim off any excess fat from the surface of the sauce. Garnish the dish with fresh lemon zest and chopped cilantro before serving warm.