Place the zucchini slices into a steamer basket and set over one inch of water in a saucepan. Bring to a boil, cover and steam for 3 to 5 minutes, or until tender. Remove from the steamer and cool slightly.
In a salad bowl, combine the zucchini and cucumber slices. In a separate bowl, whisk together the balsamic vinegar, olive oil, lemon juice, salt and pepper. Pour over the zucchini and cucumber. Toss to coat, then garnish with lemon peel.
