1. In a colander, sprinkle the cucumbers with the salt and let stand to drain for 30 minutes.
2. Pat dry.
3. Meanwhile, soak the onion in cold water for 15 minutes.
4. Drain and pat dry.
5. In a bowl, mix together the yogurt, dillweed, vinegar and sugar.
6. Add the cucumbers and onion and toss to coat.