Cook pasta: boil in well-salted water, 1 to 2 minutes past al dente. Drain, rinse with cold water, cool completely.
Make dressing: whisk olive oil, red wine vinegar, oregano, garlic powder, Dijon, salt, and pepper. Taste and adjust.
Combine: in a large bowl, add cooled pasta, tomatoes, cucumber, olives, red onion, roasted peppers, pepperoncini, and chickpeas if using.
Dress: pour dressing over salad, toss until evenly coated.
Add feta and parsley: toss once or twice lightly, keeping some larger feta crumbles visible.
Chill: refrigerate at least 30 minutes, ideally 1 to 2 hours. Taste and adjust before serving.