Rinse dried corn silk under running water; Soak it in water for 30 minutes; Remove and drain it.
Rinse, drain and slice ginger.
Remove husks of corn; Rinse and drain it; Cut it into sections.
Rinse and drain guavas; Slice off their stems; Cut them into chunks.
Rinse lean pork; Pat-dry it with kitchen paper.
Fill a deep pan with water; 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 1 minute; Immediately remove it; Rinse it under running water till cool; Drain it; Turn off the heat.
Fill a stockpot with 2500ml water; Bring to the boil over a high heat; Add all the ingredients and bring to the boil over a high heat again; Turn to a low heat; Cover the pot with its lid; Cook over a low heat for 2 hours; Scoop scum off with a perforated skimmer; Stir seasonings into the soup; Turn off the heat; Arrange the soup in serving bowls; Ready to serve.