Wash and peel and roughly grate the radiator. Wash the radishes and cut into wafer-thin slices with the washed but unpeeled cucumber, preferably with a cucumber slicer. Put everything in a salad bowl.
For the marinade, mix the vinegar with the spices and fold in the oil. Best done with a whisk. Finally fold in the sour cream. Add to the salad and mix well.
If necessary, sprinkle chopped hazelnuts on the finished salad.