Bring a large pot of salted water to a rolling boil. Add the chickpea rotini and cook for 6-7 minutes, checking at the lower end of the package time for al dente texture. Drain immediately and rinse under cold water until completely cool.

In a small container with a lid, combine the olive oil, red wine vinegar, Dijon mustard, minced garlic, salt, and pepper. Seal and shake vigorously for 30 seconds until the mixture is creamy and emulsified.

Transfer the cooled pasta to a large mixing bowl. Add the minced red onion, diced bell pepper, torn basil, cucumber, steamed broccoli florets, halved cherry tomatoes, chopped parsley, sliced black olives, and crumbled feta cheese.

Pour the prepared dressing over the pasta and vegetables. Toss everything together gently but thoroughly until all ingredients are well coated.

Cover and refrigerate for at least 30 minutes before serving to allow flavors to develop. Before serving, stir well and adjust seasoning with additional olive oil, vinegar, salt, and pepper if needed.