Place sliced cucumbers in a colander and toss with salt. Let sit for 10 minutes to draw out excess moisture, then pat dry with paper towels.
In a small bowl, whisk together rice vinegar, sesame oil, grated ginger, and sugar until the sugar dissolves completely.
Gently combine the dried cucumbers, diced avocado, and green onions in a large mixing bowl.
Pour the dressing over the cucumber mixture and toss carefully to coat everything without mashing the avocado.
Transfer to a serving dish and sprinkle with toasted sesame seeds. Garnish with fresh cilantro if desired.
Serve immediately or refrigerate for up to 30 minutes before serving for optimal texture.
