Slice cucumber, leaving peel on.
Spread butter on insides of both slices of bread for each sandwich, to taste. Usually a thin layer will suffice.
Place cucumber slices in a single layer on bottom slice of buttered bread for each sandwich, covering entire slice.
Put sandwiches together and remove crusts with knife. Some cucumber peel will come off too and that is the desired result.
Cut sandwiches into triangles.
Recipe Courtesy of David Rosengarten