Wash the cucumbers thoroughly. Cut them into thin slices, either round or half-moons according to your preference.

Place the sliced cucumbers in a large bowl. Sprinkle with salt, and mix well. Let them sit for about 10 minutes to draw out excess moisture.

In a separate bowl, combine the rice vinegar, soy sauce, chili flakes, sugar, sesame oil, and minced garlic if using. Stir until the sugar is dissolved.

After the cucumbers have released some moisture, drain them and rinse under cold water to reduce the saltiness. Pat dry with a clean towel.

In the bowl with the cucumbers, add the dressing you just prepared. Toss to ensure all the cucumber slices are evenly coated.

Sprinkle the chopped green onions and sesame seeds over the salad, and give it one last gentle toss to mix everything.

For best results, let the salad chill in the refrigerator for about 20 minutes before serving. This allows the flavors to meld beautifully.