In a small mixing bowl, combine olive oil, balsamic vinegar, oregano, dried basil, and a pinch of salt and pepper. Whisk thoroughly until emulsified.

Peel the cucumber, score the sides with a fork, slice thinly, then dice into small pieces.

Add quartered cherry tomatoes and chopped red onion (if using) into the bowl with the diced cucumber. Stir gently.

Slice mozzarella into bite-sized pieces and fold them into the vegetable mixture.

Drizzle the marinade over the salad, toss gently to combine without breaking the mozzarella.

Let the salad rest at room temperature for about 10 minutes before serving.