Preheat oven to 350°F.
Season chicken with salt and pepper, and brown in a heated pan with a glug of oil.
Remove chicken and set aside.
In the same pot, add sliced ginger and minced garlic.
Sauté until fragrant.
Pour in the mirin and use a wooden spoon to scrape up any brown bits.
Add chicken stock, miso and soy sauce.
Stir until miso has dissolved.
Add chicken back to the pot.
Cover and braise in oven for 1 hour.
While the chicken is braising, prepare shiitake mushroom rice.
In a large pot, heat sesame oil.
Add minced garlic and sauté until fragrant.
Add mushrooms and cook until soft.
Add rice and stir so everything is well combined.
Add sake and mirin and bring to a simmer.
Add water, bring to a simmer, cover and cook until water is completely absorbed, approximately 15 minutes.
Fluff with a fork.
Serve chicken with rice.
Garnish with chopped scallions.