Cut pork into 2" long pieces. Mix pork, salt, Katakuriko potato starch, and Sake, and set aside for 5-10 minutes.
Chop green onion thinly. Slice brown onion thinly. Set aside.
Mix all the ingredients for the sauce in a small bowl and stir until sugar dissolves.
In a frying pan, heat oil at medium heat, add pork, and cook until lightly browed, breaking apart. Add brown onion and cook until soft. Pour the sauce in and cook for a couple of minutes, until the sauce is slightly thickened.
Put Steamed Rice in a bowl and place pork over rice. Top with chopped green onion.