Break up the leafy vegetables with your hands.
Cut the radishes into thin rounds.
Cut the cucumber in half, remove the seeds with a small spoon, slice very thin.
Place everything into a bowl, add a few pinches of salt for taste, and mix well.
Cover bowl with a smaller flat dish, and place a weighted object (heavy jar, rock, etc.) on top of the plate to press the salad mixture. Let it stand for at least one to two hours.
When ready to serve, add one tablespoon of umeboshi vinegar diluted in a little water.
Mix well and serve.