Clean the squid thoroughly and cut it into bite-sized pieces.
Thinly slice nabak cucumber (cucumber) and onion.
Mix gochujang, vinegar, sugar, and minced garlic to make the sauce.
In a large bowl, combine the squid, cucumber, and onion, then add the sauce and mix well.
Add sesame oil and sesame seeds, and mix once more.
Transfer to a plate and serve.