Make a spicy marinade from vinegar, sweetener (let the tablets melt in the vinegar) or sugar and ½ teaspoon salt. Stir in the oil.
Peel the cucumber and slice it into not-too-fine slices. Scatter the chives on top. Add the marinade to the cucumber slices, mix everything and let it steep for about 10 minutes.
Add the sour cream and mix carefully. Sprinkle with black pepper from the mill.
This cucumber salad is well suited as a small, refreshing dinner in summer, then possibly serve with a slice of bread and butter or a pretzel.