Clean and wash the radishes. Rinse, clean, halve the cucumber and remove the seeds if necessary. Dice both very small. Rinse and quarter the apple and cut out the core. Also dice the apple quarters very small and sprinkle with 1 to 2 tablespoons of lemon juice.
In a bowl, mix the prepared ingredients together with 1 to 2 tablespoons of rapeseed or sunflower oil and season with a little salt, a few turns of colored or black pepper from the mill and, if desired, with a few chilli flakes and season to taste.
The salad goes well with jacket potatoes with or without herring, with roasted baguette or with grilled fish or steaks.