Wash and dry the English cucumbers. Trim ends and slice as thinly as possible (about 1/8-inch), preferably using a mandoline for consistency.
Place the cucumber slices in a colander and sprinkle with salt. Toss gently to distribute the salt evenly. Let rest for 5 minutes to draw out excess moisture.
While cucumbers rest, whisk together rice vinegar, sesame oil, sugar, and white pepper in a small bowl until sugar is completely dissolved.
Gently squeeze the cucumbers to remove excess water, then transfer to clean kitchen towels or paper towels. Pat dry thoroughly.
Transfer dried cucumber slices to a mixing bowl. Pour the dressing over the cucumbers and toss gently to coat evenly.
Cover and refrigerate for at least 15 minutes to allow flavors to meld.
Just before serving, sprinkle with toasted sesame seeds and chopped cilantro if using. For an authentic presentation, arrange in a neat mound on a serving plate.
