Drain the tuna. Pour the tuna into a colander. Use a spoon to press down on the tuna to remove the excess water.
Transfer the tuna to a bowl.
Then add in 1/2 a cup of mayonaise. Add more mayonaise if necessary but add in a tablespoon at a time until you are satisfied with the amount of mayo in your tuna salad. Mix to combine.
Add in the chopped onions.
Add in the chopped celery.
Add in the sweet relish.
Add the salt and black pepper.
Mix all ingredients together.
Lightly toast 6 slices of white bread . Then spread the tuna mixture onto 3 of the bread slices . Sprinkle some black pepper onto the tuna mixture and place the remaining 3 slices of bread on top. You can serve the sandwich as is or you can also add a lettuce leaf to your sandwich.
Serve with a dill pickle spear or some baby carrots & celery sticks.