How should I proceed to make a good malt vinegar. In particular I would like some recipe to know what grains (or extract) I need to use, to have a really good vinegar, not just something that is sour, since it can be bought for less than a dollar at the supermarket :)
The Mad Fermentationist has a good write-up on making malt vinegar.
Some interesting points from the article:
oxygen is key to the process so you don't want to use an airlock. A cheesecoth, or a coffee-filter over the neck of the carboy work well to keep bugs and dust out but let oxygen in.
vinegar can be made from the acetobacter in the air, but this may take longer. A vinegar mother can be bought to speed this process. While the vinegar is being fermented, the mother floats to the top to take in oxygen, ferments the ethanol into acetic acid, and then sinks to the bottom when finished.
My first batch ever was the brewers best english brown ale kit (extract). At some point it became infected and went sour. I let the bottles sit to see if it would age out (didn't know any better at the time) and the whole batch slowly turned in to carbonated vinegar.
I've used it for pulled pork and it has worked wonders on it. I still have some left and plan on using it for a pig roast that I'm doing at the end of the month.
So, to answer your question:
In my experience, the Brewers Best English Brown Ale Extract Kit makes a wonderful vinegar for pork. Ferment it out and hit it with some Acetobacter and it will go great with your summer BBQ.
You can make vinegar from any alcoholic beverage. Since there is a one-to-one ratio between ethanol and acetic acid production, use or dilute your beverage to 5-7% alcoholic strength. This is the concentration of commercially bought vinegar, usually five percent. While Acetobacter bacteria are present in the air and is carried by the vinegar fly, the use of a mother culture or unpasteurized natural vinegar will speed the process. Provide air as the bacteria requires it for the conversion. Avoid beverages that have been treated with preservatives as this will slow or prevent the growth. Moderately warm temperatures are best (70-80F) colder or extremely warm temperatures will slow the process and in the case of too much heat may produce off flavors due to an excessive formation of esters. Typically, at the proper temperature, the culture will convert 1% of alcohol into 1% of acetic acid per week. Keep the culture in a dark place and check every week for mother formation, any mold growth and evaporation.
Green Deane at Eat the Weeds explains how to make your own vinegar. Vinegar is natural. Fruit flies attracted to your wine or beer fall in and the bacteria from their guts and bodies sours the wine. The same thing with fruit. I've got an experiment on the go. I had a peach that was breeding fruit flies and the goo smells like vinegar. I washed out some goo through a filter into some sugar water and wine yeast. Also I have some Bragg's vinegar with the same. Using mason jars I have malt sugar and beer in one and just malt sugar and yeast in the other. Will see how it goes. Once it has fermented I can pasteurize it or not if it seems wholesome or ditch it if it fails. Worth a try.