Cut the cucumbers lengthwise in half. Using a spoon, gently scoop out the seeds and some of the flesh from the center to create a hollow “boat.” Repeat with the remaining cucumber halves.
In a medium bowl, combine the drained tuna, softened cream cheese, finely chopped chives, capers, salt, and black pepper. Use a fork to mix and gently mash everything together until you have a smooth, spreadable tuna rillette.
Transfer the tuna rillette into a piping cone or small piping bag. Snip off the tip to create a small opening for easy filling.
Pipe a generous amount of the tuna rillette into each cucumber boat, filling the hollow center evenly.
Cut the cherry tomatoes into quarters and place three pieces on top of each cucumber boat.
Garnish with fresh dill and finish with a light sprinkle of black pepper. Serve immediately and enjoy these fresh, creamy cucumber boats!