Boil enough water to blanch the pork spare ribs for 2 mins. Remove blanched spare ribs and rinse under tap water.
In a pot, add some oil and stir fry the ginger slices. Add preserved soy bean paste and fry for about 30 seconds. Add in the blanched spare ribs and stir fry until pork are coated with taucheo. Throw in garlic with skin on and stir.
Pour 1.5 litres of water and add dark soy sauce and mix well.
Add cut potatoes and concentrated chicken stock and bring to aa boil. Remove any scum from the surface of the soup.