Cook the elbow macaroni according to package instructions; drain and rinse under cold water.
In a large mixing bowl, combine the drained tuna and mayonnaise.
Add the diced celery and bell peppers to the bowl.
Stir in the sweet pickles and Dijon mustard.
Season with salt and pepper to taste.
Fold in the cooked macaroni until well combined.
Chill the salad in the refrigerator for at least 30 minutes.
Before serving, taste and adjust seasoning if necessary.
Garnish with fresh parsley.
Serve chilled and enjoy!