Place the cucumbers and onions in a bowl and toss with the salt. Marinate the vegetables for 3 hours.
Meanwhile, in a large saucepan, combine the sugar, vinegar, celery seeds, turmeric, mustard seeds and cloves. Bring to a boil, then continue cooking for 5 minutes.
Rinse off the marinated vegetables in cold water, and then add to the infused vinegar. Bring the vinegar back to a boil and then remove from the heat.
Cool and store in the refrigerator until ready to use. Best if used within 2 weeks.