Boil the whole wheat rotini in salted water until al dente, then drain and rinse under cold water.

Prepare the chicken by cubing pre-cooked breast or searing fresh chicken until cooked through.

Chop the cherry tomatoes, cucumber, red onion, and bell pepper into uniform pieces.

Whisk together Greek yogurt, lemon juice, olive oil, minced garlic, Dijon mustard, oregano, salt, and pepper in a small bowl.

Combine cooled pasta, chicken, and vegetables in a large mixing bowl.

Pour the dressing over the salad and toss gently until evenly coated.

Fold in the crumbled feta cheese if using.

Refrigerate for at least 30 minutes to allow flavors to meld.

Sprinkle with fresh parsley before serving.