1. Cook the gluten-free pasta: Bring a large pot of salted water to a rolling boil. Add the gluten-free pasta and cook according to package directions until al dente. Gluten-free pasta can become mushy if overcooked, so keep a close eye on it.

2. Drain and cool the pasta: Once cooked, immediately drain the pasta in a colander. Rinse it thoroughly under cold water to stop the cooking process and cool it down. This step is crucial for pasta salad to prevent it from clumping and to keep it from absorbing too much dressing while warm. Let it drain well.

3. Prepare the vegetables: While the pasta is cooking and cooling, finely chop the celery, red bell pepper, red onion, and fresh parsley. Aim for small, uniform pieces so they distribute evenly throughout the salad and provide a pleasant texture in every bite.

4. Combine ingredients in a large bowl: In a large mixing bowl, add the cooled and drained pasta. Then, add all the chopped vegetables: celery, red bell pepper, red onion, and parsley.

5. Add the dairy-free ranch dressing: Pour the entire cup of dairy-free ranch dressing over the pasta and vegetables.

6. Mix until thoroughly coated: Using a large spoon or spatula, gently toss all the ingredients together until the pasta and vegetables are evenly coated with the creamy ranch dressing. Ensure no dry spots remain.

7. Season and chill: Season the pasta salad with salt and black pepper to taste. Start with a pinch of each, mix, and then taste to adjust. For best flavor, cover the bowl and refrigerate the pasta salad for at least 30 minutes to allow the flavors to meld and the salad to chill completely.