Prepare the Cucumbers: Peel the cucumbers, slice them in half lengthwise, and scoop out any large seeds with a spoon.
Slice the cucumbers into paper-thin rounds (a mandoline works wonders here!)
Place the slices in a colander set over a bowl, toss thoroughly with 1 tablespoon (15 ml / 0.5 fl oz) of salt, and let them drain for at least 30 minutes to an hour.
Squeeze Out Excess Water: Working in batches, take handfuls of the salted cucumber slices and gently squeeze them between your palms to remove as much liquid as possible. This step is key to a creamy, not watery, salad.
Place the squeezed cucumbers in a large, dry bowl.
Mix and Combine: In a separate small bowl, whisk together the sour cream, fresh lemon juice, and sugar until smooth.
Pour this dressing over the cucumbers, add the optional fresh dill, and toss gently until every slice is evenly coated.
Chill and Serve: Taste the salad and add a tiny pinch more salt if needed. For the best flavor, cover and chill in the refrigerator for at least 20 minutes before serving to allow the flavors to meld.