Boil potatoes in lightly salted water in a large pot for 15 to 20 minutes, until just tender. Drain and allow to cool slightly.
Meanwhile, whisk together creamy salad dressing, olive oil, vinegar and salt. Set aside.
Cut potatoes into quarters and place into a large bowl. Add sliced onion, green chiles and chopped eggs. Stir until combined. Add in the salad-dressing mixture and parsley and stir gently until all ingredients are coated.
Cover and refrigerate for at least 2 hours or overnight. Makes 12 servings (9 cups).