The only blackberry you'll find in my house is the edible variety (why was the smartphone named after the fruit anyway?).
The fruit isn't quite black, however. It is - or should be - more of a deep, glossy blue-black (if it's tinged with purple-red, it's under-ripe). The plant grows wild in many parts of the United States and Europe, and while the idea of 'blackberrying' sounds quaint and fun, it can be hard work (unless you come across a particularly prolific bush). It can also be quite painful because the wild plants have thorns, although the modern cultivars have been 'bred' to be thornless.
When they're good, blackberries are sweet and very juicy, but much of the fruit sold at supermarkets can be tart, which is why I prefer them cooked. Blackberries make a delicious jam, although, because it takes a lot of ber- ries to make a decent quantity, it's probably only practical to create a preserve if you pick them yourself for free (unlikely in Hong Kong).
Their sweet-tart flavour makes them especially delicious with roasted meat. For a quick and easy sauce, melt some butter in a skillet. Add blackberries, a cinnamon stick (broken into pieces), a few juniper berries and a pinch of salt, and cook until the berries start to soften. Taste the berries - if they're very tart, add a little sugar. Stir in a splash of port or aged balsamic vinegar and simmer until the ingredients have thickened into a light sauce consistency. Add a chunk (about 15 grams) of cold butter and swirl until melted, then spoon over roasted venison, quail or duck breast.