Wash 1 English cucumber, peel if needed, trim the ends if soft, and slice into thin rounds.
Peel ¼ piece purple onion, cut in half, and slice into thin half-rounds. Separate the layers.
Peel 1 piece garlic clove and press, grate, or mash into a paste.
Chop the tender green parts of the dill.
Squeeze 1 Tablespoon lemon juice and remove any seeds.
In a small bowl, mix ⅓ cup sour cream, lemon juice, garlic, and 1 Tablespoon dill leaves.
Season with ½ teaspoon salt (or less) and ⅛ teaspoon black pepper.
In a large bowl, combine cucumber and onion. Add the dressing and stir to coat.
