Rinse raw pearl barley; Soak it in water for 3 hours; Remove and drain it;
Rinse bitter melon; Trim a bit off each base; Cut it into halves; Scrape out the seeds; Cut the remaining into slices.
Rinse, drain and slice ginger.
Rinse pork bones; Pat-dry with kitchen paper.
Fill a deep pan with water; Bring to the boil over a high heat; Blanch the bitter melon in a colander for 1 minute; Immediately remove it; Drain it.
Discard the water in the pan; Fill the pan with water again; Add the ginger; Bring to the boil over a high heat; Scald the pork bones all over in a colander with the boiling ginger water for 3 minutes; Immediately remove them; Rinse them under running water till cool; Drain them; Turn off the heat.
Fill a stockpot with 2.5L water; Add the pearl barley; Bring to the boil over a high heat; Add all the remaining 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.