Boil the Pasta: Bring a large pot of salted water to a rapid boil. Add elbow macaroni and cook for 8–10 minutes until al dente. Drain and rinse under cold water. Allow it to cool completely.

Prepare the Dressing: In a large mixing bowl, whisk together mayonnaise, ketchup, white vinegar, and sweet relish until smooth. Add salt and black pepper, adjusting to taste.

Combine Ingredients: Fold the cooled macaroni into the dressing. Add diced ham or turkey, chopped celery, and finely diced red onion. Mix carefully to incorporate all ingredients.

Chill the Salad: Cover with a lid or plastic wrap and refrigerate for at least 1 hour to let flavors meld.

Serve and Enjoy: Stir the salad gently before serving, adjust seasoning if needed, and serve chilled in a bowl.