I learnt from No Impact Man how to make vinegar out of fruit scraps, and last year I made myself a good supply. It's almost run out though, so before my last tour I started up a new batch.
It works like this: put honey in water until it tastes sweet. Wash your apples, cut away any bad bits, then put the skin and cores into the honey water. Eat the apple flesh and enjoy! Sit the honey-fruit-scraps water on the bench. After a couple of weeks it will ferment into apple cider. Leave it a few weeks more and it will turn into vinegar.
Apple cider vinegar (raw) is very useful: Take a few tablespoons in water when you have a cold to keep mucous thin (ie reduces coughing & blocked noses); take it before eating high fat food to stimulate production of bile, which will process the fats and stop you from feeling nauseous. When making stock, put the bones in a pot, add cold water and 1/4 cup of vinegar, then turn on the heat. The vinegar helps to draw the nutritional goodness out of the bones.
You can also make vinegar from other fruit scraps - a good way to avoid waste.
Anyway, I returned from tour, tasted my vinegar, and discovered it was at the apple cider stage.
AND IT IS DELICIOUS!!!!
I've bottled it up, put it in the fridge, and am now rationing myself a tiny glass every evening. I'm sure it's at least a little bit alcoholic. I'm addicted! I'm also frantically making more.
I suspect these two jars I've started will never make it to the vinegar stage. Woe! What am I gonna do for vinegar now?