Bring a large pot of salted water to a rolling boil. Add the pasta and cook until al dente according to package directions (usually 8–10 minutes). Drain and rinse under cold water to stop the cooking and cool the pasta for the salad.

While the pasta cooks, whisk together the dressing ingredients in a small bowl: olive oil, red wine vinegar, minced garlic, Dijon mustard, dried oregano, salt, and black pepper. Taste and adjust acidity and salt — the dressing should taste bright but balanced.

In a large mixing bowl, combine the cooled pasta, halved cherry tomatoes, diced cucumber, red onion, olives, roasted red peppers, and mozzarella. Gently toss so the ingredients are evenly distributed.

Pour the dressing over the pasta mixture and toss again until everything is lightly coated. Add torn basil and a final sprinkle of black pepper. If using protein like grilled chicken or chickpeas, fold them in now.

Transfer to the refrigerator for at least 30 minutes to allow flavors to meld. Serve chilled or at room temperature.