In a medium bowl, combine the cream cheese, sour cream (or mayonnaise), finely chopped dill, and kosher salt. Blend until smooth and creamy.

Spread a generous layer of the cream cheese mixture onto one side of each bread slice.

Slice the English cucumber as thinly as possible and layer the slices over half of the cream cheese-covered bread.

Top with remaining bread slices, spread side down, and gently press to seal.

Trim the crusts off the sides and cut the sandwiches into quarters.

Arrange on a serving platter and optionally garnish with dill sprigs or cucumber slices.