Onions are the indispensable vegetable, the strong (yet sweet) cornerstone of modern cooking, not just in our culture but around the world. Whether it’s a soup, stew, stir-fry, salad or sauce, chances are the recipe includes onions or garlic (very likely both) or one of their relatives. These members of the Allium genus (part of the lily family) don’t just add flavour, they add richness and complexity.


The onion is an edible bulb. While it is a vegetable at heart, it also acts as a spice inasmuch as it can provide an aromatic undertone to various meat and vegetable dishes, without being a major ingredient. The characteristic appearance is well known, but there are many variations of colour, shape and size. The colour varies from white to red to purple, the shape from spherical to almost conical, and the diameter at the largest point from 10mm (1/2in) to 8cm (3in) or ‘more. Onions should be firm, though not rock hard. The papery skin should be tight over the surface of the bulb. Spring onions, or scallions, are immature plants where the bulb has not completely formed. They may be cylindrical, the green stem shading into the white bulblet, which may be almost spherical. Onions are also available in processed form, as dried flakes and powder, or liquid.

Bouquet: Sharp. Raw onions when cut or bruised may irritate the eyes and nose.
Flavour: Generally pungent and bitter with a sweet note. Onions actually cover the whole gamut of aroma and pungency from mild to intolerable.
Hotness Scale: 3-7

Preparation and Storage

Onions may be used whole, sliced, chopped, diced or liquidised. It is important to observe the cooking instructions carefully, as the flavour of onions is greatly influenced by their treatment. A recipe where onions are to be ‘fried till golden’ will suffer if they are browned. Small onions and picklers are easier to peel if they are first immersed in boiling water for ten seconds and then rinsed in cold water before removing the skins.

To prevent the eyes from watering, peel onions under cold water or put them in the freezer for ten minutes before chopping. Should they be excessively strong, boil them whole for five minutes before proceeding with the recipe. Firm unblemished onions should keep for several weeks if stored in a cool airy place. Too much warmth will encourage sprouting. Home-grown onions must be quite dry before stringing. Dried onion flakes and powder should be stored in airtight containers.

Cooking with Onion

Onion is a basic flavouring in the kitchen. It is used as a vegetable, or as a spice to bring out the flavour of other dishes without overpowering them. It often accompanies meat – especially mince and meat dishes such as shepherds pie and meat loaf which would be insipid without it.

Onion is also widely used in soups, pickles and cooked vegetable dishes, sauces, hearty casseroles, and bean and lentil dishes. It is a common ingredient in marinades, and an onion studded with cloves is often a main flavouring in stocks and courts-bouillons.

There are many classic recipes featuring onion including such familiar dishes as tripe and onions, steak and onions, French onion soup, coq au yin, sauce soubise, to name but a few. Equally famous in India is do pvaza, a dish of meat cooked with a, much as double its weight of onions. The shallot is frequently used in Mediterranean and American cookery, the rocambole in country recipes. Spring onions are common in fresh summer salads and in Chinese and Japanese cookery.

How to Caramelize Onions

When onions are caramelized, they develop a deep sweetness and a beautiful amber color that goes all the way through the onion. It’s an easy process, you just have to be patient. It takes about 30 minutes, even longer if you want a super deep color and flavor.

  • Slice onions into thin rings .
  • Heat a large, heavy-bottomed pot or pan (cast-iron works best) over medium-high heat, then add the oil or butter.
  • When hot, add onions, stir briefly to coat, lower heat to medium and leave alone for 15 minutes.
  • After 15 minutes of not touching at all (don’t even look at them), flip the bottom layer to the top using a wide spatula. Cook for another 15 minutes without touching.
  • When most of the onions are a deep golden-brown, stir mixture together, lower heat to lowest setting and continue to cook, stirring occasionally, until all onions are dark brown and completely caramelized, up to 15 more minutes.

Onion Substitute

If the need for a substitute for onions arises because there are no onions in the house, there are several option. First, there is the possibility of substituting with a clove or two of garlic. The taste will be very close and the texture of minced garlic is very similar to that of finely chopped onion. When no garlic is available, look in the spice rack. There is a good chance that you will find onion powder or onion flakes among the spices. Both options are a great substitute for onions. As a bonus, there is no chopping or dicing involved.

Many cooks use the dehydrated onion flakes in soups, stews, and in meatloaf because they add a taste of onion without the tears. Where allergies need to be considered, you can use leeks. Leeks have a milder taste than onions and are far less acidic. Many people who cannot eat onions can consume leeks with no problem. You can use the green tops as well as the white bulbs for a little added color to the dish. When leeks are still a problem, you may want to look into such options as fried cumin seeds and perhaps asafetida, also known as hing. Both will add flavor to many recipes and may be a good choice for people that cannot handle onions for some reason.

Chemical Composition

Onion contains protein, sugars, cellulose, minerals, a fixed oil, an essential oil and over 80 per cent water. The amount of essential oil is very small but it contains the aromatic and tear-producing properties associated with onion. These are caused by sulphides which are produced by the reaction of the enzyme alliinase on an amino acid. These substances are normally in separate cells in the tissues, but when the onion is cut and bruised, rupturing the cells, the reaction takes place. Cooking has the opposite effect, preventing the enzymatic action and thus milder and less pungent flavours are produced. The chemistry of the Alliaceae family, including garlic, shallots etc, is very similar. The calorific value of raw onion is 38 calories per 100g, or roughly 20 calories for a 3oz onion.

Health Benefits of Onion

Antiseptic, diuretic, expectorant and rubefacient. Onion’s antiseptic properties as a juice or paste have been used for wound healing, skin complaints (acne), insect bites, hemorrhoids, boils, toothache, (‘as moch for that purpose as to lay an unyon to my lytel fynger for the tothe ache’, Brinklow, 1545), earache and respiratory complaints. The raw juice is diuretic and the whole onion is an appetite stimulant and digestant. It has been used as a vermifuge. It is believed to stimulate the liver and is beneficial to the heart and nervous system.

Growing Onions

A hardy biennial but cultivated as an annual. Although the bulbous plant with its long-bladed leaves has many varieties of shape and colour, it is so familiar that it is not necessary to add to what has already been said under Spice Description. A common kitchen-garden plant. It is propagated by seeds or sets. Soil: Well drained, light loam that has been manured. Sow: Mid-February through March in shallow drills 30cm (l2in) apart. Thin seedlings to 5-10cm (2-4in) apart. Plant: March-April 15cm (6in) apart in rows 30cm (l2in) apart. Aspect: Very sunny. Harvest: Salad onions when ready and other onions when leaves turn yellow. Lift and leave along rows to dry; then store in a cool dry place.

Other Names

French: oignon
German: Zwiebel Italian: cipolla S
: cebolla
Arabic: basal
Chinese: choong
Indian: palandu, pe(e)az, piaz, pyaz
Indonesian: bawang merah, daun bawang (spring onion)
Japanese: naganegi (spring onion), negi, nira (chive), rakkyo (Chinese onion), tamanegi
Malay: bawang merah, daun bawang (spring onion)
Tamil: vungium, vunguim
Thai: hua horm, ton horm (spring onion).

Scientific Name

Ailium cepa Fam: Alliaceae

Onion Recipes

French Onion Soup

Arugula, Caramelized Onion and Goat Cheese Pizza

Bulgar with Onion, Tomato, Feta and Aleppo Pepper

Photo by Wilhelm Gunkel on Unsplash ..