Wash the large cucumbers thoroughly under cold running water, then slice them thinly, about ¼ inch thick.

Sprinkle the sliced cucumbers generously with salt and let them sit in a colander for about 10 minutes.

In a medium mixing bowl, whisk together the dressing ingredients: sugar, rice vinegar, soy sauce, sesame oil, chili oil (or red pepper flakes), and minced garlic.

Rinse the cucumbers thoroughly under cold water to remove excess salt and shake gently to remove any water.

In a large mixing bowl, combine the drained cucumbers with the prepared dressing and toss together.

Slice the green onions and fold them into the cucumber mixture, then toss again until evenly distributed.

Transfer the salad to a serving bowl, sprinkle sesame seeds on top if desired, and serve fresh.