Start by bringing a large pot of salted water to a boil. Add elbow macaroni and cook until al dente, about 8-10 minutes. Drain and rinse under cold water to stop the cooking process.

In a large mixing bowl, combine mayonnaise, Dijon mustard, and a sprinkle of salt and pepper. Whisk until smooth and creamy, ensuring all ingredients are incorporated.

Add the cooled macaroni to the dressing. Gently fold in diced bell peppers, chopped celery, halved cherry tomatoes, diced red onion, and sweet pickle relish using a spatula until everything is well mixed.

Cover the bowl with plastic wrap or a lid and refrigerate for at least 1 hour.