In this dish, called Ankake Udon, the soup for the udon is thickened with cornflour and retains its heat for a long time. A perfect lunch for a freezing cold day.
To make the soup, place the water and the soup ingredients in a pan and bring to the boil on a medium heat. Remove from the heat when it starts boiling. Stand for 1 minute, then strain through muslin (cheesecloth). Check the taste and add more salt if required.