Clean, wash and quarter the cabbage. Cut out the stalk. Chop the cabbage finely. Mix cabbage and 1 1⁄2 tsp. salt and knead well with your hands. Peel onions and cut into fine strips. Peel, wash and grate carrots.
Fold under the cabbage.
Mix mayonnaise, yoghurt, vinegar and mustard. Season with salt, pepper and sugar. Mix dressing and cabbage. Leave to stand for at least 1 hour.
Wash parsley, shake dry and chop. Shortly before serving, mix into the salad.