Slice the cucumbers as thin as you can—use a knife or mandoline if you have one.
Put the sliced cucumbers in a big mixing bowl and sprinkle with salt.
Toss the cucumbers so the salt coats all the slices, then let them sit for about 10 minutes to draw out excess moisture.
Add sugar, soy sauce, rice wine vinegar, and sesame oil right into the bowl.
Mix thoroughly so the dressing covers every cucumber slice.
Sprinkle sesame seeds on top and give it one more toss to spread them around.
Chill the salad for 10-15 minutes before serving to let the flavors meld together.