Slice the cucumber thin. I did this quickly using my mandoline (I cut it into 2mm slices - 1.5mm or 1/16 inch works too depending on what model you have). Add the cucumber slices to a colander and sprinkle them with salt (about 1 teaspoon) and toss with your hands to evenly distribute it. Place colander in the sink or on a plate to catch the water that will be released. Let it sit for about 30 minutes.
Meanwhile, make the dressing by adding the sour cream, vinegar, sugar, dill, and pepper to a bowl. Taste & adjust as needed. If you prefer less sweetness, use half the suggested sugar amount. Refrigerate dressing until needed.
Chop the onion and add it to a salad bowl.
Once the cucumber is ready, give it a quick rinse in cold water and then thoroughly dry it using paper towel. Add it to the salad bowl and toss it with the dressing. It should still be salty enough, but if not, add more salt prior to serving. I recommend eating this salad within a short time of making it because it does go more watery the longer you leave it, but you can chill it for 15 minutes or so prior to serving if you wish.
Notes
Serves 4 as an appetizer or side salad. Recipe is easily doubled.
Nutritional information is provided as a courtesy only and should be construed as an estimate rather than a guarantee. Ingredients can vary and Salt & Lavender makes no guarantees to the accuracy of this information. The salt is mostly rinsed off, so it's not included as part of the nutrition info calculation, but keep that in mind if you need to consider salt for health reasons (there will still be more than indicated).