Intricately carved Moorish designs cover the walls of this friendly restaurant, which serves some of the best couscous in Paris. Zerda offers a choice of lamb, chicken, and merguez (spicy lamb sausage) versions; my favorite is the meltingly tender “lamb cooked in sauce,” but all are good. If you prefer one of the scrumptious tagines (stews seasoned with such ingredients as dried fruits, olives, or preserved lemons), be patient: They take 20 minutes to prepare.