The Onion is probably the most used and versatile vegetable available, but as there are so many different varieties and uses, we will be spreading the information over two months, starting with the basic Onion.

The Onion plant can be grown in most climates and has a fan of hollow, bluish-green leaves with a bulb at the base of the plant. In the autumn the foliage dies down and the outer layers of the Onion bulb become dry and brittle. Onions suffer from a number of plant disorders; the most serious being the Onion fly, stem and bulb eelworm, white rot and neck rot. Diseases affecting the foliage include rust and smut, downy mildew and white tip disease.

Onions are cultivated and used widely around the world. They are usually served cooked, as a vegetable or part of a prepared savoury dish, but they can also be eaten raw or used to make pickles or chutneys. They are pungent when chopped and contain certain chemical substances which can irritate the eyes. Onions contain phenolics and flavonoids that have potential anti-inflammatory, anti-cholesterol, anticancer and antioxidant properties.

The ancient Egyptians worshipped the Onion, believing its spherical shape and concentric rings symbolized eternal life. Onions were even used in Egyptian burials. In ancient Greece, athletes ate large quantities of Onion because it was believed to lighten the balance of the blood. Roman gladiators were rubbed down with Onions to firm up their muscles. In the Middle Ages, Onions were such an important food that people would pay their rent with Onions and even give them as gifts. Doctors were known to prescribe Onions to facilitate bowel movements and erections and to relieve headaches, coughs, snakebites and hair loss. Onions were taken by the first settlers to North America, where the Native Americans were already eating them raw or cooked in a variety of foods. They also used them to make into syrups, to form poultices and in the preparation of dyes. According to diaries kept by the colonists, bulb Onions were one of the first things planted by the Pilgrim Fathers when they cleared the land for cropping in 1648.

Onions are very versatile and can be baked, boiled, braised, grilled, fried, roasted, sautéed or eaten raw in salads. They can be red, white or yellow in colour. The yellow variety is used as a main ingredient in French Onion Soup or Onion Chutney, and the red variety can brighten up other dishes and salads and can also be grilled or barbequed. White Onions are traditionally used in cooking as they are sweeter in flavour and turn a golden colour when sautéed. Pearl and boiler Onions may be cooked as a vegetable rather than as an ingredient and pickling Onions are preserved in vinegar.

Onions are mainly used when fresh, although dried, fried Onion is available here in Spain and this is particularly popular as a topping to salads and dishes such as lasagne or cauliflower/macaroni cheese. Cooking Onions and sweet Onions are better stored at room temperature, in a single layer, in a mesh bag in a dry, cool, dark, well-ventilated place. In this environment, cooking Onions have a shelf life of three to four weeks and sweet Onions one to two weeks. Cooking Onions will absorb odours from apples and pears and draw moisture from vegetables with which they are stored which may cause them to decay.

The pungent juice of Onions has been used as a moth repellent and can be rubbed on the skin to prevent insect bites. When applied to the scalp it is said to promote growth of hair and on the face to reduce freckling. It has been used to polish glass and copperware and to prevent rust on iron. If boiling water is poured onto chopped Onions and left to cool, the resulting liquor can be sprayed onto plants to increase their resistance to pests and Onion plants are reputed to keep away moles and insects. Onion skins have been used to produce a yellow-brown dye.

Some people suffer from allergic reactions after handling Onions. Symptoms can include contact dermatitis, intense itching, rhinoconjunctivitis, blurred vision, bronchial asthma, sweating and anaphylaxis. Chopping Onions causes damage to cells which allows enzymes called alliinases to break down amino acid sulfoxides and generate sulfenic acids. Eye irritation can be avoided by cutting Onions under running water or submerged in a basin of water. Leaving the root end intact also reduces irritation as the Onion base has a higher concentration of sulphur compounds than the rest of the bulb. Refrigerating Onions before use reduces the enzyme reaction rate.