Slice both cucumbers into thin round discs. Place in a large mixing bowl.
Slice the onion into thin strips, then slice those strips in half moons. Place in the bowl with sliced cucumbers and add chopped green onions.
In a separate small bowl combine the rice wine vinegar, water, sugar, dried dill, salt, pepper, sesame oil, minced garlic, and roasted sesame seeds. Mix well.
Pour sauce over the cucumber and use tongs to thoroughly mix everything together.