The white onion is the bulb of a garden vegetable of the same name that belongs to the alliaceous family (like garlic). White onion is used as a vegetable and a condiment, but less commonly than the yellow (brown) onion because it is only found in spring and summer. Its smell is quite strong but its flavor is less peppery and sweeter than that of yellow and red onions. It is harvested before ripening fully.

White onions can be bought from the vegetable section of supermarkets and fruit and vegetable dealers or suppliers. They should be free from mold and have a clean, white color.

White onions are more easily peeled than yellow (brown) onions. Peeling this type of onion produces fewer tears than when peeling yellow onions, because white onions contain fewer volatile and irritating substances, particularly when kept in the refrigerator and peeled cold. Peeling under running water, or better still in a basin filled with water, limits the amount of tears produced. However, tears are difficult to avoid, because white onions need to be chopped.

White onions are always browned in a saucepan, skillet, or frying pan with a little oil and possible butter, over medium heat, because they turn dark quickly. Depending on the recipe, water or another liquid (white wine, broth, stock, etc.) is then added. The finer an onion is chopped, the faster it cooks. However, the longer it is cooked, the more its pungent aroma and flavor are diminished.

White onion can be eaten raw in salads. It can also be cooked as a confit, made into onion soup, and pissaladière. In general, white onion can be used as a condiment for a large number of sautéed, stewed, and roasted dishes.

White onions are delicate. They can be stored for about one week in the vegetable crisper drawer of the refrigerator.

The onion is a natural health food. Since time immemorial, it has been considered as both food and medicine. It contains vitamins and minerals; it is one of the best sources of selenium (a significant antioxidant in the fight against aging, among others things) in our diet. The onion has a beneficial effect on the cardiovascular system. It inhibits (especially when fresh) platelet aggregation, resulting in a lower risk of clots. It also has a hypoglycemic effect due to its sulfur compounds (50 mg per 100 g) and its large quantity of diphenylamine (the volatile substance that irritates the eyes). Finally, onions fight microbial growth, and so act as an antibacterial agent. This is why onions have always been a key ingredient in marinades. Raw white onion has a lower sulfur compound content, making it relatively easy to digest, unlike the yellow onion.