In a medium-sized mixing bowl, combine one can of solid white tuna, 1/4 cup of reduced-fat plain Greek yogurt, 1 tablespoon of extra-virgin olive oil, and the juice of half a lemon. Stir in 2 tablespoons of finely chopped shallot, 1 tablespoon of fresh chives, 1 tablespoon of chopped dill, and a sprinkle of garlic powder and ground pepper. Blend until creamy.

Take 4 slices of whole-wheat bread and lay them on a clean cutting board. Spread the creamy tuna filling on one side of each slice.

Slice fresh Persian cucumbers thinly and layer them evenly over the tuna-covered side of two slices of bread.

Place the second slice of bread, tuna-side down, onto the cucumbers to form a sandwich. Gently press down to adhere the layers.

Cut the sandwich diagonally for presentation and serve immediately.