Cook quinoa according to package directions, to yield 2 cups. Mince garlic and add to a small bowl along with the yogurt, mayonnaise, lemon juice, mint, honey and salt. Set aside. Dice zucchini, pepper and radishes. Add these to a large bowl with rinsed and drained chickpeas, cooked quinoa and dressing. Toss gently to coat. Serve salad spooned into lettuce leaves with plums on the side.