To prepare the cucumbers, place one cucumber on a cutting board and flatten, using a rolling pin or heavy-bottomed skillet, applying gentle pressure until they begin to crack but don't fully lose their shape. Repeat with the remaining cucumbers. Slice the smashed cucumbers on the bias into 1-inch pieces.
Transfer the cucumber pieces to a colander, sprinkle with salt and toss to coat. Set the colander in a large bowl and let drain for 15 minutes up to an hour in the refrigerator (this will remove some of their water, making them extra crunchy and ensuring your dressing won't get watered down).
While the cucumbers are draining, make the spicy gochujang dressing. In a medium bowl, combine the sesame oil, rice wine vinegar, shoyu, honey and gochujang and whisk until emulsifed. Taste and adjust seasonings, if necessary. Set aside.
Remove the salted cucumbers from the refrigerator and discard any extracted liquid. Pat the cucumber pieces dry with a paper towel or clean tea towel and transfer them to a serving bowl. Add the dressing and 3/4 each of the sliced green onions and toasted sesame seeds, and toss to coat.
Garnish with the remaining sliced green onions and toasted sesame seeds.
