Slice cucumbers into thin rounds or half-moons. Place in a colander and toss with salt. Let sit for 10 minutes to draw out excess water.
In a small bowl, whisk together soy sauce, rice vinegar, sesame oil, sugar, and minced garlic until sugar dissolves.
After 10 minutes, gently squeeze handfuls of cucumber slices to remove as much liquid as possible. Discard the liquid.
Transfer squeezed cucumbers to a serving bowl. Pour dressing over top and toss well to coat.
Sprinkle with toasted sesame seeds and chili slices if using. Serve immediately or refrigerate for up to 4 hours.