Wash the cucumbers thoroughly under cold water. Slice them thinly using a sharp knife or a mandoline slicer for even thickness. This ensures they absorb the dressing well.

Julienne or grate the carrots and slice the red bell pepper thinly. Chop the green onions and cilantro. Combine all the vegetables in a large mixing bowl.

In a small mixing bowl, whisk together the rice vinegar, soy sauce, sesame oil, sugar, minced garlic, and red pepper flakes. Whisk until the sugar is fully dissolved, which helps to balance the acidity of the vinegar.

Pour the dressing over the mixed vegetables in the large bowl. Toss gently to ensure all the vegetables are coated evenly with the dressing.

Let the salad sit for about 5 minutes to allow the flavors to meld. Serve chilled or at room temperature in a serving dish.