01 - Bring a large pot of salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Drain in a strainer and rinse thoroughly under cold water to halt cooking. Set aside to cool completely.
02 - While the pasta cools, halve the cherry tomatoes, dice the cucumber and both bell peppers, thinly slice the red onion, pit and halve the kalamata olives, slice the sun-dried tomatoes, and tear the fresh basil leaves.
03 - Place all prepared vegetables, olives, sun-dried tomatoes, and torn basil into a large mixing bowl. Add the cooled pasta and toss gently to distribute evenly.
04 - In a small bowl, whisk together the extra virgin olive oil, red wine vinegar, minced garlic, Dijon mustard, dried oregano, salt, and pepper until fully emulsified and creamy in appearance.
05 - Pour the dressing over the pasta and vegetable mixture. Toss thoroughly, ensuring every ingredient is evenly coated.
06 - Gently fold in the halved bocconcini and grated Parmesan, if using, taking care not to break apart the mozzarella balls.
07 - Taste and adjust salt and pepper as needed. Refrigerate for at least 15 minutes before serving to allow the flavors to meld together.
08 - Serve cold or at room temperature, garnished with additional fresh basil leaves if desired.