Wash the cucumbers and partially remove their peel in
lengthwise strips, using either a vegetable peeler or the
tines of a fork. Make sure to leave a bit of dark green
skin between each stripe.
Thinly slice each cucumber. Place the slices in a large non-metal bowl and pour on the cider vinegar, sugar, salt, and pepper. Stir or toss the mixture gently until the sugar is dissolved.
Add the onion slices and fresh dill, then toss well to combine. Let the mixture marinate for at least half an hour before serving.
It's best to serve any leftovers at room temperature. So refrigerate any remains, but let the seasonings be enhanced by a little time on the table before dining.