Peel cucumbers and cut them into thin slices. If they are very ripe, remove seeds. Mix with the salt, making sure that every slice is salted. Add more salt if needed. Let the slices stand for 30 minutes or, if you have time, for as long as 2 hours.
Meantime, peel the onion and cut into hair-thin slices. Place in a mixing bowl and add the sugar, paprika, vinegar and ½cup water.
By now the cucumbers will have released almost acup of liquid. With your hand press out as much as you can from the slices. Discard the liquid.
Put the cucumber slices into the bowl with the onion dressing. Mix well. Since the cucumbers have already been salted, it’s possible that you won’t need to add any, but if necessary add up to ½teaspoon. Adjust vinegar and water according to your taste for vinegar.
Serve in individual glass or porcelain salad dishes.