ONION
Onions are maybe the most basic aromatic vegetables that are widely used in stocks, sauces, stews, and a heap of other dishes. Their pungent smell and flavor fits good with almost anything, and the common onion cooking technique of sweating it in oil is probably known to everyone who ever set their step in a kitchen. Onions, besides their aromatic flavor, also come with lots of vitamin C, fibers, and chromium, as well as some amounts of other vitamins and minerals. In short, onion is an all-round good-tasting and nutritious vegetable, and it is said that eating half an onion a day keeps the cancer away (this remains to be proven though, but there is some truth in this saying). It is so that onion contains lots of a special antioxidant molecule called quercitin, which was shown to be able to reduce precancerous lesions in the human digestive tract - therefore onions are said to prevent the cancers of the gastrointestinal system.
Onions are known for making people cry, or at least producing tears. The reason are the very volatile molecules that fly into the air and irritate our eyes. One way to avoid this common problem is to light a candle near the cutting board, so the flying irritants will become destroyed. Another way is to simply wear a pair of goggles. Yet another way is to chill the onion in the refrigerator first before you start to chop it - coldness will reduce the volatility of the molecules. Many tear-avoiding tricks have been designed throughout the culinary history, and we just list a few of them. You might have your own tricks up your sleeve perhaps?
Onions are vegetables that grow by packing layers of flesh above each other. This is evident already when you peel the onion skin. There are several types of onions as well, the classical yellow one is the most widely used, however there are also red onions, shallots, spring onions, and silver onions, all of which have a slightly different taste. Some onions are more or less sweet, and some are more or less intense in flavor. From the health perspective, the more the onions taste, the more healthy they are, since they contain more of the good health-promoting molecules. One way to tell if the onion is indeed more healthy than the other is by experiencing the amount of the tears generated when you chop it. More tears means more health!
When buying onions choose the ones that have an unblemished skin without any dark and soft spots. They should have a good shape and not be open, that is they should have their skin intact all over the flesh. Bad onions have rotten dark and soft areas, can be mouldy, and can also have sprouts. These onions should be avoided.
Store the onions at room temperature, preferably in a dark compartment with good air ventilation. Onions keep well for quite a few days, but they need to be stored away from ethylene-generating veggies (e.g. potatoes), which would spoil the onion more quickly. If you have cut or chopped the onion, you need to store it wrapped in a plastic foil in a refrigerator and use it within a day, or it will deteriorate quickly.