For a decorative touch, dip one end of a finished sandwich into mayonnaise and then into minced fresh parsley before serving.
Ensure cucumbers are thoroughly dried after draining to prevent the bread from becoming soggy.
If fresh chervil is unavailable, you can substitute with extra tarragon or a mix of parsley and chives.
These sandwiches are best served fresh but can be assembled up to 2 hours in advance if kept covered and refrigerated.
Use a mandoline slicer for uniform, paper-thin cucumber slices.