In a large mixing bowl, drain the tuna from three cans and add to the bowl. Use a fork to break the tuna into smaller pieces.

Finely chop one stalk of celery and half a medium onion, and add them to the bowl.

Pour in half a cup of creamy mayonnaise and fold the ingredients together until well combined.

Add two tablespoons of sweet pickle relish and mix thoroughly, then season with salt and pepper to taste.

Toast slices of bread if desired, spoon generous servings of the salad onto the bread, and add optional toppings like lettuce and tomato.

Let the tuna salad chill in the refrigerator for about 30 minutes before serving for optimal flavor.