Thinly slice the cucumbers, either leaving the peel on or peeling them according to your preference.
Slice the white onion into rings.
Place the sliced cucumbers in a clean dish towel and roll the towel, squeezing firmly to remove excess moisture from the cucumbers.
Transfer the squeezed cucumbers to a mixing bowl and add the onion rings.
Pour enough white vinegar over the cucumbers and onions to cover them, adding a small amount of cold water and a hint of sugar to the vinegar.
Season the cucumbers and onions with salt to taste.
Sprinkle freshly ground black pepper over the salad mixture, adjusting the amount to your preference.
Refrigerate the cucumber and onion salad for several hours or overnight to allow the flavors to meld and the salad to chill thoroughly.
Serve the refreshing cucumber and onion salad cold as a delightful side dish or light appetizer.