Wash the cucumbers thoroughly under cold running water and dry them completely. Using a sharp knife or mandoline slicer, cut the cucumbers into thin, even slices about 3 mm thick. Uniform thickness ensures the cucumbers absorb the dressing evenly and maintain a consistent texture throughout the salad. If using cucumbers with large seeds, slice them lengthwise first and gently scrape out the seeds with a spoon before slicing. Place the sliced cucumbers in a colander set over a bowl or sink and sprinkle them lightly with a small pinch of salt. Toss gently to distribute the salt evenly. Allow the cucumbers to rest for 10 minutes, which draws out excess moisture through osmosis and prevents the dressing from becoming watery. After resting, gently pat the cucumbers dry using paper towels or a clean kitchen towel. Avoid squeezing them aggressively, as this can damage their texture.

Thinly slice the red onion into delicate half-moons using a sharp knife or mandoline. If the onion flavor is particularly sharp, place the slices in cold water for 5 minutes, then drain and pat dry. This step removes some of the raw onion bite while preserving its crisp texture and mild sweetness. Finely chop the fresh dill for the dressing, reserving a small portion for garnish later.

In a medium mixing bowl, combine the sour cream, white vinegar, honey, minced garlic, salt, and black pepper. Whisk thoroughly until the dressing becomes completely smooth and emulsified. The honey should dissolve fully so that the dressing develops a balanced flavor with mild sweetness, acidity, and creaminess. Stir in the chopped dill and mix until evenly distributed. Taste the dressing and adjust seasoning if necessary. The dressing should taste slightly tangy and well seasoned on its own since the cucumbers will dilute the flavor slightly once mixed.

Add the prepared cucumber slices and red onion to the bowl with the dressing. Using a large spoon or spatula, gently fold the vegetables into the dressing until every slice is evenly coated. Work slowly to avoid breaking the cucumber slices. Ensure that the onions are evenly distributed throughout the salad so that each serving contains a balanced combination of flavors.

Cover the bowl and refrigerate the salad for at least 30 minutes before serving. This resting time allows the cucumbers to absorb the creamy dill dressing while the flavors of garlic, vinegar, and herbs meld together. Before serving, give the salad a gentle stir to redistribute the dressing. Transfer to a serving bowl and garnish with additional fresh dill. Serve well chilled for the most refreshing flavor and texture.