Making vinegar starts with a culture, just like yoghurt or sourdough bread. Add wine and 12 months to this list for wonderful vinegar that will impress any foodie — and it gets better with time.
The Eater's Digest says that you can purchase starter cultures from winemaking shop,s but you can also just buy any bottle of unpasteurised vinegar from a supermarket or local market. Save the leftover bits of wine that are not consumed until you have at three litres or so.
When you're ready to begin, fill an oak barrel or ceramic pot with your unfinished wine, an equal amount of water and the vinegar starter culture. It will take a year for the batch to become fully ready to use, but if you're bitten by the vinegar bug, you can start new batches every few months. This way, you will frequently have new batches of vinegar maturing.
From Alice's Green Kitchen: Making Your Own Vinegar [The Eater's Digest via Punk Domestics]