The sweet and sour flavors of pickle brine accentuate and complement some of the natural flavors of tuna, allowing the tart brine to gel with the salty fishiness of canned tuna.
Instead of stirring in mayonnaise with your tuna salad, add chopped pickles and dress with a few tablespoons of pickle brine and notice how it unites all the ingredients.
This tip can also work in chicken, potato, or macaroni salad. If this inspires you to take things further, it can also be blended into a punchy pickle brine vinaigrette.