Sour wine is usually the result of either chemical spoilage, due to too much sulfur dioxide produced during fermentation, or microbial spoilage as a result of storage conditions such as temperature. Sour wine is instantly recognizable from the sharp taste on your palette. You will never create a fine wine from a sour one, but there are several ways in which you can fix sour wine to make it quaffable or, at the very least, suitable for use in cooking.
Make sangria. Pour the sour wine into a jug along with an equal measure of lemonade or tonic water. Add ice and chopped fruit. Leave to chill and then drink.
Make mulled wine. Pour the sour wine into a small saucepan and place on a cooking hob. Add 2 tbsp. of brown sugar and spices like cinnamon and cloves. Bring to a boil and then turn the heat down. Leave to simmer for 10 minutes before drinking.
Make a reduction. Sour wine can be used in cooking as the basis of a sauce. Pour the wine into a large saucepan, place on the cooking hob and bring to a boil. Add carrots, onions, celery and other vegetables, as well as spices. Reduce the wine down until it is very concentrated. Add sugar to sweeten slightly if necessary.