How to make your own vinegar
For something that smells so foul, vinegar does marvelous things to dishes. Without it, vinaigrettes would be impossible, mustard and ketchup would have no tang, and a lot of marinades couldn't please a taste bud if they tried. That's why it's so great that the culinary industry has caught on to how versatile an ingredient vinegar can be and have flooded shelves with different flavors, colors and types.
However, like all things, vinegar is a lot better if you make it yourself, and if you've resolved to cook more at home in the coming year, add vinegar to the list of things you're going to prepare yourself. You just need something to start with (wine, Champagne, etc.) and a mother, which you can find online. Add time and then love the vinegar you make.
Buying your vinegar mother
“Mother” is the term for the collection of helpful bacteria which will go about the business of converting your alcohol into vinegar. It's important to have a good mother because all vinegar is essentially spoiled liquor, but not all spoiled liquor is vinegar. It's possible to have bacteria go to work on your alcohol and turn it into something disgusting, so make sure that you're turning your precious liquor into vinegar by having a good mother.
Obviously in the days before the internet, there were ways you could produce your own mother and if you can find some unpasteurized vinegar, feel free to leave it out and you'll end up with homemade mother. However, in this day and age, it's just as easy to go to a wine making shop or buy what you want online. Also, there are different mothers for different types of liquor (for instance, a white wine vinegar mother, a cider mother, etc.), so make sure you know what kind of mother you have.
Also, if you're just starting off, buy a white wine mother. They're about as foolproof as they come.
A quick word on the mother itself. When you finally have your mother, whether you made it or bought it, be prepared for a little shock. The mother looks a lot like the killer blob from a bad science fiction film, only less appetizing and will smell only slightly better than it looks. However, don't be afraid of it. That ugly thing will make the magic happen.
Making the vinegar
To make the vinegar itself, wash one or more glass containers with warm soapy water and rinse thoroughly. The soap won't hurt the mother, but it won't taste good, either.
Next, pour in some of the mother and swish it around the glass container so that all parts of it are coated. Pour in enough alcohol so that the container is three-quarters of the way full, then top with cheesecloth.
Put the container somewhere warm and come back in two weeks. As long as no green or white mold forms in the vinegar, after two weeks you shall have vinegar. Use a slotted spoon to remove any of the mother floating in it (which you can keep), and then pour the vinegar into another container. Store in the refrigerator for several weeks.