In season mid-winter: Onions

New Zealand’s top onion-growing area is Pukekohe, south of Auckland. Other than brown onions, there are red onions – often called Spanish onions (large, round and reddish-brown skinned) shallots or ‘gourmet onions’ (smaller, sometimes clustered onions), and spring onions (known as scallions or green onions in the US). Red onions are mild and sweet, shallots have a finer texture and sweeter taste, and spring onions are milder than brown onions and so they are often used raw.

Buying

Choose brown and red onions with crisp, dry outer skins. Avoid onions and shallots with signs of decay: soft spots, moisture at the neck and dark patches. Select shallots which are firm and heavy for their size. Choose spring onions with dark-green crisp leaves and firm, white bulbs.

Storing

While spring onions can be stored in a plastic bag in the fridge for up to one week, keep other varieties out of the fridge as other food may absorb the onion flavour. Store other onions ‘plastic-bag free’ somewhere cool and airy. Ensure onions are kept separately from potatoes, too, to avoid spoilage from ethylene gas and moisture. If stored in a cool, dark, airy place, onions can keep for up to two months.

Nutrition

Research shows that onions may help guard against many chronic diseases. That’s probably because onions contain generous amounts of a flavonoid called quercetin. Studies have shown that quercetin protects against cataracts, cardiovascular disease, and cancer. Onions also contain naturally occurring chemicals known as organosulfides that appear to be potentially protective for heart disease, stroke and deep vein thrombosis as they have strong blood thinning properties. It is also thought organosulfides may increase the high-density lipoprotein (HDL) or good cholesterol and lower the low-density lipoprotien (LDL) or bad cholesterol.

Using

Onions add flavouring to savoury dishes and are highlighted in dishes such as French onion soup and onion marmalade.