Overview

The garden onion, Allium cepa var. cepa, is the common bulb onion, a biennial plant cultivated for its layered, pungent bulb. It is the most widely grown Allium species globally and provides a foundational savory flavor across many cuisines, ranging from sharp and astringent when raw to sweet and caramelized when cooked.

Origin and history

The garden onion is believed to have originated in Central Asia, likely in the region encompassing modern-day Iran, Pakistan, and the mountainous areas of Tajikistan and Uzbekistan [1]. It has been cultivated for over 5,000 years, with evidence of use in ancient Egypt, where it was depicted in tomb paintings and considered a symbol of eternity [2]. The onion spread through trade routes to Europe, Asia, and eventually the Americas with European colonization. It has since become a staple crop in nearly every agricultural region of the world.

Varieties and aliases

  • Common bulb onion (the standard dry onion found in most grocery stores)
  • Yellow onion (the most common variety, with brown-gold skin and balanced flavor)
  • Red onion (purple-skinned, milder and often used raw)
  • White onion (white papery skin, sharper flavor, common in Mexican and Latin American cooking)
  • Sweet onion (low-pungency varieties such as Vidalia, Walla Walla, or Maui)
  • Spring onion or scallion (immature plants harvested before bulb formation; note that many scallions come from Allium fistulosum (bunching onion) rather than A. cepa; here only immature bulbs of A. cepa var. cepa are intended)

Culinary uses

The garden onion is a universal aromatic base, often sautéed in fat as the first step in soups, stews, sauces, and braises. It can be eaten raw in salads, salsas, and sandwiches, where its sharpness is moderated by soaking in cold water or acid. Caramelizing onions over low heat develops their natural sugars into a deep, sweet, brown paste used in French onion soup, tarts, and relishes. Onions are also pickled, fried into rings, roasted whole, or used as a flavoring stock ingredient.

Cross-cuisine context

The garden onion is used worldwide as an aromatic base in countless savory dishes, forming the foundation of many stews, soups, and sauces across diverse culinary traditions.

Notes for cooks

  • Store dry bulb onions in a cool, dark, well-ventilated place, away from potatoes, which emit moisture and gases that cause onions to spoil faster.
  • To reduce tearing when cutting, chill the onion for 30 minutes before slicing, or cut under running water.
  • The intensity of an onion’s pungency correlates with its pyruvate content; sweeter varieties have lower pyruvate levels and are better suited for raw applications [2].