Mix soy sauce, sugar, stock, and mirin together in a bowl. Arrange meat and vegetables on a large platter. Heat an electric skillet to 375 degrees F.
Add oil to the skillet and heat. Brown meat in the oil, adding sugar slowly. Move the meat to the corner of the skillet when well browned. Add other vegetables, keeping each separate. Add sauce and cover. Bring to a boil and cook for 2 minutes. Uncover and turn all ingredients while cooking 2 minutes more. Serve on small plates.