Score cucumbers by running the tines of a fork down the sides. Slice very thin;
place them, along with the onions, in a deep bowl. Press down on the cucumbers with
the palms of your hands to release some of the juices.
Sprinkle with sugar, parsley
and dill; toss and pour vinegar over.
Let sit at room temperature for 30 minutes,
then press again. Juice should cover cucumbers.