Trim off both ends of the cucumber. Lay it on a cutting board and smack it a few times with the flat side of a Chinese cleaver, knife blade, or heavy rolling pin until it splits into large pieces. (To prevent the seeds from flying out over your counter, you can also place the cucumber in a zip-top bag or wrap it in a towel first.) Cut the split cucumber at a diagonal into ½-inch bite-sized pieces. Place them in a medium bowl and sprinkle evenly with the salt, then cover and refrigerate for 15 minutes.
Drain off any water the cucumber has released (without rinsing off the salt). Add the garlic, sugar, soy sauce, vinegar, sesame oil, and chili oil and toss to coat, adjusting the seasonings to taste; more soy sauce for savoriness, more vinegar for acidity, or chili oil for extra aroma and heat. Let sit in the fridge to marinate for 30 minutes before serving.
The cucumbers will keep in an airtight container in the fridge for up to a week.
