Combine the rice vinegar, minced chiles, salt, and mirin in a glass bowl. Add the sliced scallops and toss to coat. Cover and refrigerate for 30 minutes. Add the green onion and sesame seeds, gently stirring to mix.
Arrange the cucumber slices on each of 4 plates. Spoon the scallop mixture on top of the cucumbers and garnish with the julienned chiles. Drizzle with soy sauce and serve.
Yield: 4 servings