Drain the lentils and place in a large bowl. Add the vinegar, olive oil and vegetable stock.
Cut the spring onions with the leek into small rings and the peppers into small cubes. Peel and dice the kohlrabi. Cut the apples unpeeled into small sticks. Put the vegetables, dressing and apples in a bowl and mix well.
It is best to let it steep in the refrigerator overnight or for a few hours. Add a small dash of water if necessary.