In a medium mixing bowl, combine smooth peanut butter, soy sauce, vinegar, and sesame oil. Whisk until smooth.

Wash and dry the cucumbers, then slice into thin rounds or half-moons. Place in a large mixing bowl.

Drizzle the dressing over cucumbers and gently toss to coat evenly.

Cover and refrigerate for at least 15 minutes to let flavors meld.

Give a final toss and serve cold, garnishing with sesame seeds or chopped peanuts if desired.