Remove the scales and guts from the mackerel and wash it thoroughly.
Rinse the rice and soak it for about 30 minutes.
Slice the shiitake mushrooms, carrot, and green onion thinly.
Add the soaked rice and water to the pot and season with soy sauce and cooking wine.
Place the prepared mackerel and vegetables on top of the rice.
Cover with a lid and cook over medium heat for 10 minutes, then on low heat for an additional 10 minutes.
Turn off the heat and let it steam for 10 minutes.
Mix the finished pot rice well and serve in a bowl.