Slice the cucumbers into 1/4-inch thick rounds and place them in a colander. Sprinkle with sea salt and let sit for 10 minutes to draw out excess moisture.
In a mixing bowl, whisk together low-sodium soy sauce, rice vinegar, granulated sugar, minced garlic, chili flakes, and toasted sesame oil until the sugar dissolves.
Rinse the salted cucumbers under cold water and pat them dry with a clean kitchen towel. Add the cucumbers to the dressing and toss to coat evenly. Allow the salad to marinate for a few minutes before serving.