Prepare the Cucumbers: Wash and peel the cucumbers (if preferred). Slice them thinly into rounds or half-moons using a knife or mandolin slicer.
Make the Dressing: In a bowl, combine the soy sauce, rice vinegar, sugar, sesame oil, minced garlic, and chili paste (if using). Stir until the sugar dissolves and everything is well mixed.
Toss the Cucumbers: Add the sliced cucumbers to the bowl with the dressing. Toss gently to ensure the cucumbers are evenly coated. Let sit for 5 minutes to absorb the flavors.
Garnish and Serve: Top with sesame seeds and fresh cilantro or green onions. Serve immediately or refrigerate for a few hours to intensify the flavor.