1. Cook couscous, rice, or pasta according to package directions. Fluff couscous with fork, if using. If using rice, make sure all liquid is absorbed so the rice is dry, not sticky. If using orzo, rinse hot pasta in cool water and drain well.
2. In a medium mixing bowl, combine cucumber, tomato, pepper, onion, olives, chickpeas, and parsley.
3.In a small mixing bowl, whisk olive oil, lemon juice, and garlic. Season to taste with salt and freshly-ground black pepper.
4. Add dressing to vegetable mixture and toss well.
5. On a serving dish, arrange lettuce leaves, mound the couscous, rice, or pasta in center and cover with mixed vegetables.
6. Sprinkle with feta, if using, and serve.
