Prep the cucumbers: Use a mandoline to thinly slice the cucumbers. Toss the sliced cucumbers with sea salt and let stand until the moisture is drawn out, about 3 to 6 minutes, depending on thickness. Squeeze out the excess moisture. Taste and rinse if it's too salty. Otherwise, leave it as is.
Dressing: Combine the rice wine vinegar, sugar, soy sauce, and sesame seeds in a bowl. Whisk to dissolve the sugar.
Serve: Toss the cucumbers with the dressing and serve immediately or chilled. Enjoy!
