Overview

Red onions are cultivars of the common onion (Allium cepa) distinguished by purplish-red skin and white flesh tinged with red. They are medium to large in size and have a milder, less pungent flavor than yellow or white onions. Red onions are available year-round and are notably high in flavonoids and dietary fiber compared to other common onion types [1].

Origin and history

The common onion is believed to have originated in Central Asia, with domestication dating back over 5,000 years in regions that include modern-day Iran and Pakistan [2]. Red-skinned varieties emerged through selective breeding over centuries and are now grown worldwide. The specific history of red onion cultivars is less documented than that of the species as a whole, but they have become a staple in Mediterranean, Latin American, and Middle Eastern cuisines.

Varieties and aliases

  • Red onion (standard English name)
  • Cebolla morada (Spanish, used across Latin America)
  • Cebolla roja (Spanish, less common)
  • Purple onion (colloquial English)

Culinary uses

Red onions are most commonly used raw, where their mild pungency and color add bite and visual contrast to salads, salsas, and garnishes. They are the dominant raw onion in Guatemalan and Salvadoran table preparations such as curtido, chirmol, and pickled garnishes. In Peruvian cuisine, red onion is foundational: it appears in salsa criolla (raw red onion with ají and lime), as the base of aderezo (the sautéed aromatic foundation of many criollo dishes), and in ceviche, where it is sliced thin and cured in lime juice alongside fish. Red onions also appear in Persian Salad Shirazi (finely diced with cucumber and tomato), Armenian fasolia (white bean salad with sumac), and Peruvian lomo saltado (stir-fried with sirloin, tomato, and ají amarillo). They can be roasted, grilled, or pickled, though cooking diminishes their color and much of their flavonoid content.

Cross-cuisine context

Red onion is the default raw onion across multiple LA-relevant cuisines. In Mexican and Central American cooking, it is the standard onion for curtido (the fermented or pickled cabbage slaw of El Salvador and Guatemala) and for chirmol (a fresh tomato-onion salsa). In Peruvian cuisine, red onion is the only onion used in ceviche and salsa criolla; yellow or white onions are considered incorrect substitutions. In Persian cooking, red onion is the standard choice for Salad Shirazi and for raw accompaniments to kababs. In Armenian meze, it appears in bean salads dressed with olive oil and sumac.

The closest analogue in Japanese cuisine is the milder, sweeter Kōbe or Tokyo market onion (a yellow variety), but red onion has no direct analogue in traditional Japanese cooking; it appears in modern fusion contexts. In Korean cuisine, the standard raw onion is a white or yellow variety, though red onion is sometimes used in ssam (wraps) or pickled banchan. In Vietnamese cooking, red onion is not traditional; shallots and white onion are more common, though red onion appears in modern interpretations of dishes like bò lúc lắc (shaken beef).

Notes for cooks

  • Red onions are milder than yellow or white onions. Soaking sliced red onion in cold water for 10–15 minutes reduces pungency further and crisps the texture.
  • The red color is water-soluble and will bleed into other ingredients. For pickling, use a vinegar-based brine to help set the color.
  • Store in a cool, dry, dark place with good air circulation. Refrigeration is not recommended for whole onions but is acceptable for cut pieces in a sealed container for up to 7 days.