Place sliced cucumbers in a strainer and toss with the 1 tbsp of salt. Let sit over a bowl or in the sink for 20 minutes to drain off excess water.
I like to soak my red onions in ice water for 5 minutes to remove some of the pungency and soften the flavor. However, since soaking too long will dilute the flavor, soaking in cold water for 5 to 10 minutes is recommended.
In a bowl whisk the sugar, vinegar, buttermilk, yogurt, dill, salt, and pepper.
Drain and add the onions.
After 20 minutes rinse the cucumbers well in cold water and drain.
Add the cucumbers and toss.
Let sit a minimum of 30 minutes and serve cold.