Place a fine-mesh strainer over a bowl. Halve 1 pound Persian cucumbers lengthwise, then cut crosswise into 1 to 1 ½-inch pieces. Cut each piece in half diagonally.

Place the cucumber pieces in the strainer, sprinkle with ½ teaspoon of the kosher salt, and toss to combine. Let sit for at least 30 minutes or up to 1 hour — the salt will draw the water out of the cucumbers. Meanwhile, prepare the wakame, dressing, scallions, and herbs.

Place 1 tablespoon dried wakame in a medium bowl and cover with ¼ cup water. Set aside to hydrate for at least 10 minutes. Pat dry with a paper towel, then coarsely chop. You should have about ¼ packed cup chopped, hydrated wakame.

Place 2 tablespoons rice vinegar, 1 tablespoon mirin, ½ teaspoon hondashi or ¾ teaspoon fish sauce, ½ teaspoon granulated sugar, the remaining ½ teaspoon kosher salt, and ¼ teaspoon red pepper flakes in a large bowl. Whisk until the sugar, hondashi, and salt are dissolved. Whisk in 1 tablespoon toasted sesame oil.

Thinly slice 2 medium scallions, keeping the whites and greens separate. Add the scallion whites to the wakame. Place the scallion greens in a small bowl. Tear 2 tablespoons cilantro leaves and 2 tablespoons mint leaves into small pieces, add to the scallion greens, and toss to combine.

Add the salted cucumbers, wakame, and scallion whites to the vinegar mixture and toss to combine. Let marinate, stirring occasionally, for 5 to 10 minutes.

Taste and season with more kosher salt, granulated sugar, or fish sauce as needed. Add 1 ½ teaspoons of the sesame seeds and half the herb mixture, and toss to combine. Transfer the cucumber mixture with the juices to a serving platter. Drizzle with ¼ to ½ teaspoon chile oil if using. Sprinkle with the remaining 1 ½ teaspoons sesame seeds and remaining herb mixture.