1 (12") cucumber
Salt
1 tbsp. good olive oil
1 tbsp. lemon juice
Scant tsp. sugar
Freshly ground white pepper

The cucumber must be cut as thin as possible, using a mandoline or a food processor fitted with a metal blade. Very lightly salt the slices and leave them to drain in a colander, lightly weighted with a plate, for 2 hours or so, pressing from time to time to get rid of the excess juices.

Combine the sliced and drained cucumber with the oil, lemon juice, sugar and a dredge of freshly ground white pepper (no more salt). Spread thin slices of white or brown bread with creamed butter; fill in the usual way, but at the last possible moment, as this sandwich can become soggy.