Place the chicken breast in a microwave-safe container. Sprinkle with salt, sake, and 1 tablespoon of water (not listed). Cover loosely with plastic wrap and microwave at 600W for 1 minute 30 seconds. Flip and heat for another 1 minute 30 seconds. Let cool, then shred finely.
Thinly slice the spring onion. Slice the cucumber lengthwise and then diagonally. Combine both in a bowl and arrange on a plate.