A member of the lily family, onions are used in most savoury dishes and many salads. They come in a number of colours and sizes.
The most commonly used and probably the best are brown onion. They come into season in late summer, are at their best in autumn and are still good in early winter.
Red onions are supposed to be milder in flavour and are commonly used raw in salads. But in fact, they are more extreme than their russet coloured cousins. They start their season in late spring and last through autumn. That they are at their best during the hotter months may explain their use in salads. Currently they are the most fashionable onion.
White onions are milder in flavour and sweeter than the brown brothers.
Spring onions are immature onion that haven't developed a bulb. The white and green parts are used and they have a sharp fresh taste much valued in Asian cooking.
Pickling onion are small versions of the white and brown varieties and, as their name suggests are used for pickling, or their visual appeal.
Onions are related to garlic, leeks, shallots, chives and asparagus.