Onion in the general sense can be used for any plant in the Genus Allium but used without qualifiers usually means Allium cepa L., also called the garden onion. Onions (usually but not exclusively the bulbs) are edible with a distinctive strong flavour and pungent odour which is mellowed and sweetened by cooking. They generally have a papery outer skin over a fleshy, layered inner core. Used worldwide for culinary purposes, they come in a wide variety of forms and colors. Onions are available in fresh, frozen, canned, and dehydrated forms. Onions can be used, usually chopped or sliced, in almost every type of food, including cooked foods and fresh salads, and as a spicy garnish; they are rarely eaten on their own but usually act as accompaniment to the main course.
- Depending on the variety, an onion can be sharp and pungent or mild and even sweet.
- Chopped, it is one of the three vegetables considered the holy trinity of Louisiana Creole and Cajun cuisine.
- Cocktail onions, or pickled pearl onions, are used to garnish drinks such as Gibsons.
They appear to be at least somewhat effective against colds, heart disease, diabetes, osteoporosis, and other diseases and contain anti-inflammatory, anticholesterol, anticancer, and antioxidant components such as quercetin.