1. Halve cucumbers lengthwise and scrape out seeds.
2. Slice cucumbers 1/8-inch thick.
3. Transfer to colander set over a bowl.
4. Sprinkle cucumbers with salt and refrigerate.
5. Combine vinegar, sugar and rice wine vinegar in small saucepan.
6. Bring to a boil, shaking pan gently to dissolve sugar; remove from heat.
7. Cool to room temperature.
8. Transfer to serving bowl and chill thoroughly.
9. Add cucumbers and dill (if desired) and toss lightly.
10. Cover and refrigerate at least 8 hours or overnight.