Make the dressing. In a medium bowl, combine the sour cream, salt, sugar, and white vinegar. Stir until smooth.
Prep the fresh dill. Pull the feathery little sprigs off the ends of the dill stalks (discard the tough stalks). Gather the sprigs together, twist or roll them up finely, then run your knife down and through them to get finer pieces. You want about a tablespoon. Stir the dill into the dressing — it'll smell wonderful right away.
Peel and slice the cucumbers. Peel your cucumbers (it's fine to leave a little bit of the peel on here and there if you'd like). Cut off the ends and slice them into rounds about a quarter to a half inch thick. If your cucumbers are on the larger side, 2 may be plenty; if they're smaller, use 3 or 4.
Combine. Add the cucumber slices to the dressing and stir well. The cucumbers tend to stick together, so make sure you separate them and get the dressing coating each piece.
Serve or chill. You can serve this immediately, or chill it in the fridge for a couple of hours before serving. Either way works beautifully.
This salad is best the first day or two. Because of the high water content in cucumbers, it doesn't keep much longer than that.
Stir it again every time you serve it — the cucumbers release water as it sits, so the dressing needs redistributing.