Place sliced cucumbers in a bowl. Sprinkle with salt and toss to coat. Let sit for 15 minutes to draw out excess moisture.
Drain the cucumbers and gently squeeze out any remaining liquid.
In a separate bowl, whisk together the rice vinegar, soy sauce, sesame oil, sugar, garlic, and gochugaru.
Add the cucumbers and green onions to the dressing and toss well.
Sprinkle with toasted sesame seeds before serving.