AUTUMN is surely upon us; watercress has arrived in the wet markets. Time to stock up on almonds, figs, and dates: all essential ingredients for watercress soups which 'lubricate the lungs' (so say the Cantonese) during the dry weather ahead.
Watercress, or sai yeung choi as it is locally known, appears in the markets in great tangled heaps. For those who know it as a delicate ingredient of dainty summer sandwiches and light salads, this may offend sensibility. For the Cantonese, however, watercress is little more than a weed which happens to be tasty. It is grown in wet ditches, requiring little attention, harvested in bunches and used generously, primarily in soups.
Identify watercress by its deep green colour, often tinted red-purple, by the irregular shape of its leaves (lyre-shaped, with six to eight distinct, rather oval leaflets per leaf), small and closely spaced towards the tip, larger and widely spaced towards the base of the green stems. Note, too, the small white roots often found growing at the bases of leaves along the lower stems.
When buying, you want as much tender green tip and as little thick leafless stem as possible. You must select by the heap rather than by the stalk; that is, patronise the vendor with the freshest, most luxuriant heap in which all the stalks have bushy tips.
When cooking watercress, boiling it for several hours turns the vegetable limp, olive-green, and stringy but yields a delicious broth highly valued for its ability to clear phlegm from the respiratory system and to cleanse and cool the blood.
Another good reason to boil it is the local means of cultivation, which is to grow it in muddy ditches and otherwise stagnant water where all sorts of creatures can breed and come to market clinging to the many leaves. Hence, the first and critical step in preparation for anyone eating local watercress - particularly anyone who intends to eat it raw - is to wash it carefully. Discard the yellowing lower leaves and toughest lower inches of stems.