Clean, wash and thinly slice or slice the radishes. Clean the spring onions, rinse and cut into thin rings. Rinse the parsley, shake dry and finely chop the leaves. Drain the capers and mash them lightly with a fork if necessary.
For the vinaigrette, mix the vinegar with lemon juice, salt, pepper and possibly a pinch of sugar, then beat in the oil in a thin stream and stir in the capers or the cucumber cubes and the chopped parsley.
Mix the radishes with the spring onions and the vinaigrette in a salad bowl.