Cut the cucumbers into thirds, then cut each third into quarters. They should be about 2-inches in length.
Transfer cucumbers to the bowl and add salt. Mix thoroughly. Set aside for 20 to 30 minutes.
After 20 to 30 minutes has passed, you should see a pool of water at the bottom of the bowl with cucumbers. Drain the cucumbers well and transfer to a new bowl.
Toss in the garlic chives, onion, scallions, and garlic. Add gochugaru, sugar, fish sauce, white vinegar, and sesame seeds.
Using your hands (with gloves on), mix everything together, making sure to rub the seasoning into the cucumber.
Serve immediately or transfer to the fridge to chill for up to 4 days.
