Combine the cucumbers and salt in a large, shallow bowl; cover and chill 1½ hours. Move the cucumbers into a colander and rinse thoroughly under cold water. Drain well, and return the cucumbers to bowl. Add the onion to the bowl.
Combine the sugar and the remaining ingredients in a medium saucepan; bring to a simmer over medium heat, stirring until sugar dissolves. Pour the hot vinegar mixture over the cucumber mixture; let stand at room temperature 1 hour. Cover and refrigerate 24 hours. Store in an airtight container in refrigerator up to 2 weeks.
Notes
I like to play around with this recipe and put in different ingredients from time to time like substituting some red onion for the sweet onion, or omitting the garlic if I don't want that garlicky punch.