Peel the cucumbers and slice them into very thin rounds—a mandoline slicer works beautifully here and ensures even, delicate slices that will absorb the dressing properly. Place the sliced cucumbers in a large bowl and toss with the thinly sliced red onion, salt, and black pepper. Let this mixture sit for about 5 minutes; the salt will begin to draw out excess moisture from the cucumbers, which prevents a watery salad.

In a separate bowl, whisk together the sour cream, apple cider vinegar, sugar, garlic powder, and fresh dill until smooth and well combined. I like to add the vinegar gradually while whisking to ensure the sour cream stays creamy without curdling. Taste the dressing and adjust the seasoning if needed—it should have a pleasant balance of tang, creaminess, and subtle sweetness.

Pour the dressing from Step 2 over the cucumber and onion mixture from Step 1 and fold gently until all the vegetables are evenly coated. Transfer to a serving bowl or individual containers and refrigerate for at least 2-4 hours, or up to overnight. I find that chilling allows the flavors to meld beautifully and gives the salad its traditional, refreshing quality. When ready to serve, use a slotted spoon to portion out the salad, leaving excess dressing behind if you prefer a less creamy bite.