Remove the tendon from the chicken tenders. Place them in a microwave-safe container, sprinkle with sake and salt, cover loosely with plastic wrap, and microwave at 600W for 2 minutes. Let cool and shred into large pieces by hand.

Cut off both ends of the cucumber and slice thinly. Sprinkle with a pinch of salt (not listed in ingredients), let sit for 5 minutes, rinse with water, and squeeze out excess moisture. Thinly slice the shiso leaves.