Combine cucumbers and salt in a colander and place over a bowl or in the sink. Allow to sit for 20-30 minutes.
Place salted cucumbers on a layer of paper towels and pat dry.
Combine red pepper flakes, rice vinegar, gochujang (if using), sesame seeds, garlic, sesame oil and sugar in a bowl.
Add cucumbers and toss well.
Serve chilled.