Wash and dry the cucumber and tomatoes. Slice the cucumber into 1/4-inch thick rounds.
Slice the tomatoes into 1/4-inch thick slices. If using cherry tomatoes, halve them instead.
Drain the mozzarella balls if they're packed in liquid. If using larger mozzarella, tear into bite-sized pieces.
Arrange the cucumber slices, tomato slices, and mozzarella on a large serving platter or shallow bowl.
Scatter the fresh basil leaves over the arranged ingredients.
In a small bowl, whisk together the olive oil, balsamic vinegar, salt, and pepper until well combined.
Drizzle the dressing evenly over the salad.
Let the salad sit for 5 minutes to allow the flavors to meld before serving.
