Slice cucumber thinly and sprinkle lightly with salt. Let sit in a colander for a few minutes to remove excess moisture.
In a mixing bowl, combine cream cheese, dill, lemon juice, salt, and pepper until smooth and spreadable.
Spread the cream cheese mixture evenly over all slices of bread.
Layer cucumber slices on half of the bread slices, close with remaining bread, and press gently.
Cut sandwiches into halves or quarters and serve immediately.
Notes
Best enjoyed fresh. To prepare ahead, keep cucumbers and spread separate until ready to assemble to avoid sogginess. Try adding smoked salmon or herbs for variation.