Wash and dry the English cucumber thoroughly.
Using a sharp knife or mandoline slicer, cut the cucumber into very thin slices.
Place the cucumber slices on paper towels and sprinkle lightly with flake sea salt and black pepper.
Let the cucumbers rest for about 5 minutes to release excess moisture.
Spread the softened chive and onion cream cheese evenly over 4 slices of bread.
Arrange the cucumber slices on top of the cream cheese, slightly overlapping each slice.
Sprinkle with additional flake sea salt and pepper if desired.
Add fresh dill for extra flavor and freshness.
Top with the remaining bread slices to complete the sandwiches.
Trim the crusts from all sides.
Cut each sandwich into triangles or small squares and serve immediately.