1. In a medium bowl, combine the softened cream cheese, mayonnaise, fresh dill, fresh chives, lemon juice, garlic powder, 1/4 teaspoon of the kosher salt, and black pepper. Stir until the mixture is smooth, creamy, and well combined.

2. Wash and dry the English cucumber. Slice it into very thin rounds or ribbons using a sharp knife or mandoline. Lay the slices on paper towels and lightly blot to remove excess moisture. Sprinkle with the remaining 1/4 teaspoon kosher salt and set aside.

3. Lay the slices of soft white sandwich bread on a cutting board. Trim off the crusts so you have neat, even squares of bread.

4. Spread a thin layer of softened unsalted butter on one side of each slice of bread to create a moisture barrier that keeps the sandwiches from becoming soggy.

5. Spread a generous layer of the herb cream cheese mixture over the buttered side of half of the bread slices, taking it all the way to the edges.

6. Arrange the cucumber slices in a single, slightly overlapping layer over the cream cheese on each prepared slice of bread.

7. Top each with a second slice of bread, buttered side facing down, to form full sandwiches. Press very gently so the cucumbers and spread adhere.

8. For the cleanest cuts, transfer the sandwiches to the refrigerator for about 15 minutes to firm up slightly.

9. Use a sharp serrated knife to cut each sandwich into 4 small triangles, rectangles, or squares, wiping the knife between cuts for neat edges.

10. Arrange the cucumber tea sandwiches on a platter, garnish with extra dill or cucumber slices if desired, and serve chilled.