Rinse the bean sprouts in water and set them aside.
Add 200 ml of water to a pot, place the bean sprouts on top, cover, and boil over high heat for 4 minutes; while they cook, thinly slice the green onion.
As soon as the sprouts are done, rinse them in cold water to cool.
Tip.After rinsing in cold water, don't squeeze the sprouts too hard—just shake off the excess gently. A little residual moisture helps the seasoning blend more smoothly.
In a large bowl, combine the bean sprouts, green onion, guk-ganjang, minced garlic, sesame oil, and sesame seeds, tossing well; adjust the seasoning with a pinch of fine salt to finish.