Quarter the cucumbers lengthwise and slice off the center portions to remove the seeds. Cut the lengths into 2-inch-long pieces.
Put the cucumbers in a bowl, sprinkle with the salt and garlic, and mix well. Cover and refrigerate for 20 minutes.
When you are ready to serve the salad, drain the juice that the salt has extracted from the cucumber pieces, retaining as much of the garlic and scallions as possible. And arrange the cucumbers on a plate.
Pour the sesame oil and red pepper flakes over the cucumbers and serve cold.