Grass-jelly herb
A whole dried plant, stems and leaves (仙草, Platostoma palustre), boiled two hours into a black, slightly viscous liquid that is thickened with cornflour, rice flour and tapioca starch and chilled into the black jelly of the herbal-tea shop's glass case. Taiwan calls it 仙草 and serves it warm and soft as 燒仙草; the Hong Kong 涼粉 is the firm, cut one. In Australia the dried herb is a Chinese herbalist or larger Asian grocer item, labelled 涼粉草, 仙草乾 or dried grass jelly herb; the tins of ready grass jelly and the instant 仙草粉 sachets at every Asian grocer are what most families actually use.
Preparation
Rinse well (a whole dried plant carries grit), soak twenty minutes, and after boiling strain through cloth, pressing the herb hard.
Origin
Guangdong, Guangxi and Taiwan. Dried herb at Chinese herbalists and larger Asian grocers; tins and instant powder at every Asian grocer, and 1 kg grass-jelly powder online.
Availability in Australia
Herbal shops / specialists
Where · Chinese herbalists and larger Asian grocers (dried herb); every Asian grocer (tins, powder); Bubble Tea Supply AU online (powder)
What to ask for · Ask for 涼粉草 or 仙草乾
If it is not there · The tin of grass jelly; nothing else is 涼粉