Most commercial pickles are preserved with vinegar, which is the product of one kind of fermentation. But sour pickles develop their complex flavor thanks to lactic fermentation, the process by which the naturally occurring bacteria Lactobacillus transforms and preserves foods, usually in a brine. The balance of salinity is key: You want enough salt to get a nice, crisp pickle and to prevent the growth of pathogens or mold, but not so much that the pickles are unpleasant to eat.
While vinegar-making microflora will spontaneously gather on your wine, you may choose to kick-start the process with a mother of vinegar culture. This red wine vinegar is flavored with star anise and cloves, and makes an excellent all-purpose seasoning for everything from salad dressings to marinades.