Their flavour is mild, and the entire onion, including top, stem, and bulb, is used raw in salads and sauces, as a garnish, and also as a seasoning for prepared dishes. Onions are low in nutrients but are valued for their flavour. Most whole onions are slightly dried before marketing, making their skins dry and paper-thin. Leading world producers of dry onions include China, India, the United States, Russia, Japan, and Turkey. Spain is the leading European producer.
Onions are also available in various processed forms.
Boiled and pickled onions are packed in cans or jars. Frozen onions are available chopped or whole, and bottled onion juice is sold for use as a flavouring. Dehydrated onion products have been available since the 1930s. Processing involves elimination of most of the moisture by heat or by freeze-drying. Such products include granulated, ground, minced, chopped, and sliced forms.