In a large mixing bowl, combine rice vinegar, olive oil, sesame seeds, and red pepper flakes. Whisk until well emulsified and slightly thickened.

Prepare the fresh ingredients by finely chopping cilantro, dicing cucumbers, slicing celery, and chopping scallions.

Gently add the vegetables into the bowl with the dressing and fold until everything is evenly coated.

Sprinkle salt and pepper over the salad mixture to enhance flavors and gently toss.

Cover the bowl and refrigerate for at least 30 minutes to allow flavors to meld.

When ready to serve, toss the salad gently and transfer to a serving bowl.