Dried, preserved sour plums (called wah mui or suen mui in Cantonese) are something you have to have grown up with to appreciate. They can be almost overwhelmingly intense - the natural sweet-sour flavour of the fresh fruit is exaggerated through drying, then enhanced but also balanced by the different seasonings, which can include salt, sugar, licorice and citrus peel.
Their appearance is off-putting to the uninitiated - they've been described as resembling the cat's contribution to its litter tray. They can be glossy, shrivelled, moist and dark, pinkish-red or brownish-tan and dusty looking. Some are seedless.
The moist varieties (the dark ones) come wrapped in pairs, first in cellophane then in white paper marked with colours to indicate what they've been flavoured with. The red and brown types tend to be drier, with the former usually sweeter and the brown ones salty.
Dried plums are believed to be good for digestive problems and for preventing nausea, although if you have high blood pressure they should be eaten in moderation because they often contain lots of salt.
In addition to being eaten plain, preserved plums are put into cups of inexpensive rice wine to make it more palatable. They can also be steeped in boiling water then served with ice to make a refreshing drink, or ground and sprinkled over fresh fruit.
Traditional Chinese snack shops sell the largest variety of dried plums; Aji Ichiban also carries a good selection.