Wash cucumbers and pat dry
Slice cucumbers into thin rounds or half-moons
Thinly slice red onion and mince the garlic
In a bowl, whisk together vinegar, soy sauce, sesame oil, sugar, salt, and pepper
Add cucumbers, onion, and garlic to the bowl
Toss until everything is well coated
Sprinkle with sesame seeds, chili flakes, and fresh herbs
Chill for 10–20 minutes, if time allows, for flavors to develop