Vegetables for vitality: onions

There are very few kitchens where onions are not found. White, brown and red onions, which are left in the ground to mature and have a tough outer skin for longer storage, are used almost daily. Fresh scallions or shallots should be purchased as needed. Read on to learn more about this kitchen staple.

Packed into 125 millilitres (half a cup) of chopped onion:

• 30 calories
• vitamin C to fight infection
• a phytochemical known as diallyl sulfide that is thought to lower the risk of stomach cancer
• quercetin, another phytochemical that fights cancer and heart disease

Season

Onions are available all year round. While at their peak in spring, spring onions (long and thin with a bulb at the end) and green onions (long and uniformly thin) are also available all year.

What to look for

Choose firm, evenly shaped onions and spring onions with smooth, brittle, papery skin. Avoid onions that have soft spots or wet, discoloured skin. Spring onions should be a bright white, with deep green leaves and fresh-looking roots. Spring onions and green onions are juicy and mild enough to eat raw.

Storing

• Store onions in a mesh bag in a cool, dry open space away from bright light.
• Don't store them with potatoes; the potatoes give off moisture and a gas that causes onions to spoil more quickly. They should keep up to a month.
• Milder, sweeter onions such as Vidalia onions and eschalots often don't keep as long as sharper-tasting onions.
• Spring onions are not meant to be stored for long periods. Wrap them in plastic, refrigerate and use within a few days of purchase.

Preparation

Onions contain a substance called a lachrymator, which is released into the air when the vegetable is peeled or cut. When these vapours combine with moisture from your eyes, sulfuric acid is formed, resulting in a painful burning sensation and tears. To prevent or minimize this, try peeling the onion while holding it under cold running water.

Some people suggest chewing on a piece of bread while you chop, to stop tears from forming. If you use a sharp knife and make quick work of chopping, tears won't be too much of a problem. Onions are best chopped by hand. If you use a food processor, pulse gently off and on to avoid mashing the onion.

Basic cooking

Onions can be steamed, microwaved, battered and deep-fried, roasted or grilled on their own to be served with meat, poultry or fish as a side dish. But onions are most often used – raw or sautéed – to season soups, stews, sauces, cooked vegetables, casseroles, stir-fries and stocks.

• Caramelizing is a popular way to cook onions to accompany meat.
• To serve four, thinly slice three yellow onions. In a heavy pan over medium heat, heat 15 millilites (one tablespoon) of olive oil. Add onions and cook, covered, for 10 minutes, stirring often.
• Remove cover; cook for 10 more minutes, stirring occasionally.  A pinch of sugar speeds the caramelizing process, producing browned, soft, aromatic onions to complement any dish.

• Cook sliced red or sweet white onions in olive oil over low heat until they are very tender and golden brown. Serve them with meat, fish or poultry, or as a hamburger relish.
• Stuff large sweet onions that have been cored with a seasoned rice mixture. Bake in the same way as you would stuffed peppers.
• Add sautéed onions and chopped fresh dill to bread doughs.
• Stuff cored apples with sautéed red onions and bake until tender. Serve with sausages and scrambled eggs for brunch or a light lunch.