The word tagine refers to both a gently simmered North African stew and the conical cooking vessel used for stewing meats and vegetables in their own juices. Serve this sweet-spiced stew of eggplant and golden squash over couscous with a dab of harissa, the fiery Moroccan chili paste. If you can't find ras el hanout, a Moroccan spice blend, substitute cumin and coriander in equal amounts. The 1/2 preserved lemon can be replaced by 1 1/2 tsp. fresh lemon juice plus 1/8 tsp. salt.