There's a delightful unpredictability to homemade vinegar. You choose the main ingredient – pretty much any unfortified booze from scrumpy to French champagne – but after that nature takes over. All the hard work is done by microorganisms called acetic acid bacteria, which convert the ethanol in the drink to acetic acid, the substance that gives vinegar its kick.

The process will take months, and you can never be entirely sure what flavours will be introduced. It's a lot like making unadulterated cider, where you place your taste buds at the mercy of natural field yeasts and sugars. And it's every bit as rewarding.

To get started, take a litre or two of wine, cider or real ale, some clean cloth or kitchen towel, a piece of string or a rubber band, and a glass, ceramic or stainless steel jar or pot. This must be big enough to take the liquid with plenty of room to spare. (You could even treat yourself to a purpose-made vinegar crock, shaped like an amphora and with a little tap at the bottom.)

Clean the container, pour in the liquid, and tie or seal the cloth over the neck. (Do not use cling film or anything that will produce an airtight seal.) Put it somewhere warm and not too light, and eventually – it might take six months or more – the contents should be transformed into vinegar by those naturally occurring acetic acid bacteria. These slowly form a translucent "mother of vinegar" that floats on the surface, gradually thickening until it sinks in a gelatinous mass to the bottom of the container, where it can be ignored until you feel like cleaning it out.

You can cut the wait by months by adding ‘mother’ or acetic acid bacteria. Pour a large glass of this into your container.

Your nose and taste buds will tell you when your vinegar is ready.

Vinegar doesn’t really go bad. It may form another film on the surface if it’s left for a long time, but that can be taken care of by straining it away. As well, the flavour may continue to get stronger by the week, but that can be corrected with a little more water.

Don't worry if it looks a little cloudy – that'll be the mother, which you can filter out at the bottling stage.

Keep topping up the vinegar crock with your leftover cider/wine and you will have a never-ending supply of natural vinegar.