Zucchini and Cucumber Salad

I did a variation on this recipe tonight for dinner and we really liked it. I needed to make note of it so I wouldn't forget (as is often the case).
Zucchini and Cucumber Salad
2 or 3 small zucchinis, thinly sliced
2 or 3 small cucumbers, thinly sliced
1 or 2 tomatoes, diced (or cherry or pear tomatoes cut in half)
1/2 sweet onion, thinly sliced
2 Tbsp flat-leaf parsley, chopped
1/3 cup extra virgin olive oil
1/4 cup cider vinegar (I just used white vinegar)
3 Tbsp balsamic vinegar
1/2 Tbsp dijon mustard
1/2 tsp salt
1/8 tsp garlic powder

In a large bowl, combine zucchini, cucumber, onion, tomatoes, and parsley. For dressing, whisk together oil, vinegars, mustard, salt, and garlic powder. Add to zucchini mixture; toss to coat. Season cucumber salad with additional salt and pepper. If desired, cover and chill up to 24 hours.

Update: I cut up pieces of day-old ciabatta bread and added it to the salad the next day for lunch--beyond fabulous! Seriously--that was the best panzanella salad I think I've ever had.