Wash the cucumbers thoroughly and slice them into thin rounds, about 1/8 inch thick.

Peel and thinly slice the shallot. If too sharp, soak in ice water for 10 minutes.

Mix seasoned rice vinegar, sugar, grated ginger, sea salt, dried red chile flakes, and soy sauce in a medium bowl until dissolved.

In a large jar or bowl, add sliced cucumbers and shallots, then pour over the pickling brine.

Cover and refrigerate for at least two hours, preferably overnight, for best flavor.