Poke chicken breast a few times with a fork. Massage it with miso and black pepper in a big heat-resistant bowl and set aside for 10 minutes.
Place the chicken breast (from instruction 1) with the skin-side up and roll it to make a chicken stick. Peel and thinly slice a 1 inch (2.5 cm) piece of ginger. Add cooking sake, water and gingers. Cover the bowl with plastic wrap loosely and microwave it at 1200W for 2 minutes 45 seconds. Let it cool. (Cooking time depends on the wattage of your microwave.)
Cut the white part of Japanese green onion into strips. Chives or corianders can be used instead of Japanese green onion. Combine [A] for sauce.
Cut the breast (from instruction 2) into diagonal pieces approx. 0.4 inch (1 cm) thick.
Transfer the chicken on a plate with the sauce (from instruction 3) on top. Serve the liquid left in the bowl in a small bowl as chicken soup.