Drain the canned tuna thoroughly and flake it into small, flaky pieces using a fork, placing it in a medium bowl.
Finely dice the celery into small, crisp pieces to add crunch and vibrant color.
Dice the red onion finely, then rinse the pieces in cold water to mellow its pungency. Drain well and add to the bowl with tuna.
In the bowl, combine the flaked tuna, diced celery, and red onion, mixing gently with a fork to distribute evenly.
Add the mayonnaise to the mixture and fold gently until the ingredients are coated evenly, creating a creamy texture.
Squeeze the juice of half a lemon over the mixture, then gently stir to brighten the flavors and balance the richness.
Stir in the capers or chopped pickles for an extra briny punch, if using, and sprinkle in the chopped herbs for freshness.
Gently fold all ingredients together, then taste and adjust seasoning with more lemon or herbs if desired.
Cover the bowl and refrigerate for about 10 minutes to allow flavors to meld and the texture to firm up slightly.
Give the salad a final gentle stir and serve chilled, garnished with a sprig of fresh herbs if desired, on its own or over greens or bread.