In a large bowl, combine the drained tuna, chopped celery, and relish.
Add the mayonnaise and Dijon mustard, then mix until well combined.
Season with salt and pepper to taste. Adjust the ingredients to your preference.
Chill the tuna salad in the refrigerator for at least 15 minutes to let the flavors meld.
Serve on your favorite bagel, bread, crackers, or lettuce wraps. For extra texture and flavor, top with sliced tomatoes, cucumbers, or hard-boiled eggs.
