Remove the skin from the chicken and, starting at the center, butterfly it to the left and right sides to make it evenly thin (kannon-biraki cut). Cut into 1cm pieces.
2.
Place the chicken in a zippered freezer bag, add the Plus Koji Shio Koji and mirin (a) and massage to coat well. Spread thinly in the bag.
3.
Cut the onion into large wedges. Break the maitake into large pieces. Cut the green pimento and bell pepper into large bite-sized pieces.
4.
Place the vegetables in the bag on top of the chicken, spreading evenly. Remove the air from the bag, zip closed and freeze.
5.
Place the vegetable oil in a frying pan with the frozen chicken and vegetables, vegetable side down. Sprinkle over 2 tbsp of water, cover and cook for 4 minutes.
6.
Break the chicken and vegetables up and turn the chicken over. Cover and cook for a further 4 minutes.
7.
Remove the lid and continue cooking until all the liquid evaporates and the chicken browns. Transfer to a serving plate.
