In a large mixing bowl, combine the wild-caught tuna, clean mayo, diced red or yellow onion, kosher salt, freshly ground black pepper, paprika, and freshly squeezed lemon juice. Use a fork to thoroughly mix the ingredients until you achieve a creamy, well-blended consistency. This flavorful mixture should appear moist and aromatic, taking about 5 minutes to prepare.

Wash and dry the cucumbers, then carefully slice them into 1/2-inch thick rounds using a sharp knife. Aim for uniformity to ensure even sandwich assembly. You can partially peel the cucumbers for aesthetic appeal and added texture. Arrange half of the cucumber slices on a large platter or plate, ready for filling.

Using a spoon or small ice cream scoop, place a generous dollop of the tuna mixture onto each cucumber slice laid out on the platter. Ensure an even distribution, covering the entire surface of each cucumber round.

Take the remaining cucumber slices and gently press them atop each filled cucumber round to create a sandwich effect.

Optionally, skewer each cucumber sandwich with a toothpick for easy serving, especially helpful for gatherings.

If you're not serving the sandwiches immediately, cover the platter with plastic wrap and refrigerate for up to an hour to allow flavors to meld together.