Peel the cucumber and slice into medium-thickness slices about one-eighth-inch (3mm) thick. Lay the slices flat on a large plate in layers, salting each layer well. Leave for about ½ hour in the fridge to allow some of the water to drain out. Meanwhile place the yoghurt into a mixing bowl and liberally add freshly-ground pepper. Stir well.
Remove the cucumber from the fridge and drain off the water. Place the slices in a clean tea-towel or thin cloth and squeeze gently to remove more of the moisture. Open the cloth, separate the cucumber slices and add them to the yoghurt. Stir well and serve.