1. Place the cucumbers in a mixing bowl and sprinkle with the salt, tossing well to combine. Gently massage the salt into the cucumbers for about 1 minute and set aside.

2. Combine the vinegar, bonito flakes, and sugar in a small saucepan and bring just to a simmer over medium-high heat, stirring to dissolve the sugar. Cool the mixture quickly by placing the pan in a bowl filled with ice. Set aside.

3. Transfer the cucumbers to a small glass or ceramic dish, discarding any liquid left behind in the bowl. Pour the vinegar mixture over the cucumbers and marinate them in the refrigerator for at least 2 hours, turning the pieces over once or twice.

4. To serve, lift the cucumbers from the marinade, briefly shaking the slices to remove any excess liquid. Place the cucumbers on small serving plates, overlapping the slices in an attractive pattern (a small circle works nicely). Top the cucumbers with a bit of sliced scallion and a light drizzle of chile-sesame oil.