The onion is believed to have originated in Asia, though it is likely that onions may have been growing wild on every continent. Dating back to 3500 BC, onions were one of the few foods that did not spoil during the winter months. Our ancestors must have recognized the vegetable's durability and began growing onions for food.
The onion became more than just food after arriving in Egypt. The ancient Egyptians worshipped the onion, believing that its spherical shape and concentric rings symbolized eternity. Of all the vegetables that had their images created from precious metals by Egyptian artists, only the onion was made out of gold.
Today, onions are used in a variety of dishes and rank sixth among the world's leading vegetable crops. Onions not only provide flavor; they also provide health-promoting phytochemicals as well as nutrients.
Uncut onions keep a long time but onions start to deteriorate after they are cut. If you buy onions of different sizes you can often find one the size you want for the recipe you're doing. If a recipe calls for just half an onion and you don't want to throw the other half away you can cut the other half up, bag it and freeae it. That way later when you need another half onion you've got half an onion cut up and ready to use.
- White Onion- is a type of dry onion that has a pure white skin and a sweet, mild white flesh.
- Red Onion- sometimes called purple onions, are cultivars of the onion with purplish red skin and white flesh tinged with red.
- Bulb onion – Grown from seed (or onion sets), bulb onions range from the pungent varieties used for dried soups and onion powder to the mild and hearty sweet onions, such as the Vidalia from Georgia or Walla Walla from Washington that can be sliced and eaten on a sandwich instead of meat.
- Multiplier onions – May refer to perennial green onions, or to onions raised from bulbs that produce multiple shoots, each of which forms a bulb. The second type is often referred to as a potato onion.
- Tree onion or Egyptian onion - Produce bulblets in the flower head.
- Welsh onion – Sometimes referred to as green onion or spring onion, although these onions may refer to any green onion stalk.
- Yellow onion - generally tapered ends, brown skin over the onion.
- Sweet onion - flatter ends and sold individually. Spanish and Vidalia
Unlike onions where each plant normally forms a single bulb, shallots form clusters of offsets, rather in the manner of garlic.
Shallots are extensively cultivated and much used in cookery, in addition to being excellent when pickled. Their flavor is perhaps more delicate than that of onions, perhaps more intense. Certainly it is distinctive. Finely sliced deep-fried shallots are used as a condiment in Asian cuisine. Shallots tend to be considerably more expensive than onions, especially in the United States where they are almost exclusively imported from France.
Scallions, or green onions, or spring onions are edible plants of the genus Allium. The upper green portion is hollow. They lack a fully developed root bulb. Harvested for their taste, they are milder than most onions. They may be cooked or used raw as a part of salads or Asian recipes. Diced scallions are used in soup, noodle and seafood dishes. To make many Eastern sauces, the bottom quarter-inch of scallions are commonly removed before use. Scallions haven't got a bulb while (green onions/spring onions) have a small bulb. What Americans call green oinions are called spring onions is Canada, the United Kingdom and some other nations which causes some confusion.
Scallions, green onions and spring onions can be used fairly interchangeably in cooking but spring onions have a more intense flavour when used raw.