Slice the cucumbers lengthwise into very thin strips, about 0.5 mm thick. Use a mandoline slicer or vegetable peeler to get even slices.
Gather a few cucumber slices and gently roll them into a spiral. Repeat with the remaining cucumber slices.
Arrange the cucumber ribbons close together in a large glass serving dish.
In a small bowl, mix the soy sauce, mirin, chili oil, honey, garlic, and green onion.
Pour the dressing evenly over the cucumber ribbons. Cover and refrigerate for at least 1 hour.
Sprinkle with sesame seeds.