Cucumber Tea Sandwiches

1 or 2 European cucumbers
salt and black pepper
White wine vinegar
Pumpernickel or wheat bread, thinly sliced (I used one slice white, one slice wholemeal)
Butter, at a spreadable consistency

Peel the cucumbers and slice into transparent slices with a fine, sharp knife, a mandolin or even a potato peeler.
Sprinkle slices with a little of the vinegar and salt and let drain in a sieve for 30 minutes. Drain away any excess liquid and pat dry with a paper towel. Butter the bread and cover with two layers of the drained cucumber. Season with pepper and top with another slice of buttered bread.
Press down on the sandwich while cutting off the crusts. You can flatten further using a rolling pin. Cut into small rectangles or triangles.
Cover with plastic wrap until time to serve.