Step 1: Soak the Red Onion - Thinly slice the red onion and soak in ice water for at least 30 minutes.

Step 2: Cook the Elbow Macaroni - Cook elbow macaroni in salted water until al dente, then drain and cool.

Step 3: Prep the Vegetables - Chop celery and bell pepper into small pieces.

Step 4: Whisk Together the Dressing - Combine Catalina dressing, mayonnaise, dill pickle relish, salt, and pepper in a bowl.

Step 5: Combine the Ingredients - Add red onion, macaroni, celery, and bell pepper to the dressing and mix well.

Step 6: Chill Before Serving - Cover and refrigerate for at least one hour before serving chilled.