Combine minced chicken, soy sauce, grated ginger and potato starch in a bowl. When the mixture is combined, add water and mix well until the water is absorbed completely.
In a medium sized pot, place mushrooms and bok choy and pour water, then bring to boil over high heat. When the water boils, turn down the heat and drop the chicken mixture into the pot by making a ball-shape with hand and a spoon. Cover with a lid and cook them over medium-low heat for 3 minutes.
Add Udon and cook for extra 1.5-2 minutes. Just before turning off the heat, mix the soup base in.
Transfer to a serving bowl and sprinkle with Shichimi for your preference.