Wash and dry the cucumbers, strawberries, and mint. Slice the cucumbers into half-moons about 1/4-inch thick. Hull and quarter the strawberries. Thinly slice the red onion if using. Stack the mint leaves, roll them up, and slice into thin ribbons.
In a small bowl or jar, whisk together the olive oil, vinegar, honey, salt, and pepper until emulsified.
In a large bowl, combine the cucumbers, strawberries, red onion, and mint. Pour the dressing over and toss gently to coat.
Let the salad sit at room temperature for 10 minutes before serving to allow flavors to meld. Serve immediately or refrigerate.