Rinse chestnuts under running water; Drain them; Make a small incision in the skin with a paring knife to avoid their explosion; Fill a deep pan with water; Bring to the boil over a high heat; Add the chestnuts; Cook over a high heat for 6 minutes; Remove them with a wire skimmer; Turn off the heat; Leave them to cool a bit; Peel off the tough shells and the papery thin skin underneath while the chestnuts are still hot.
Rinse and drain dried noble dendrobium.
Rinse and drain cordyceps militaryis.
Rinse dried honey dates under running water and drain them.
Rinse, drain and slice ginger.
Rinse lean pork under running water; Pat-dry with kitchen paper; Cut it into chunks.
Discard the water in the deep pan; Fill it with water again; Add the ginger; Bring to the boil over a high heat; Scald the lean pork all over in a colander with the boiling ginger water for 3 minutes; Immediately remove it; Rinse it under running water till cool; Drain it; Turn off the heat.
Fill a stockpot with 2.5L water; Bring to the boil over a high heat; Add all the ingredients; Bring to the boil over a high heat again; Turn to a low heat; Cook over a low heat for 2 hours; Stir seasonings into the soup; Turn off the heat; Arrange the soup in serving bowls; Ready to serve.