Heat oil in a large nonstick skillet over medium-high heat. Add zucchini, onion, carrot, and garlic; sauté 5 minutes. Stir in broth and the next 9 ingredients (broth through tomatoes); bring to a boil. Cover, reduce heat, and simmer 8 minutes or until tender, stirring occasionally.
While the chickpea mixture simmers, prepare couscous. Bring water to a boil in a medium saucepan; gradually stir in couscous. Remove from heat; cover and let stand 5 minutes. Fluff with a fork.
Serve the stew over couscous.