red onion
See also: onion
An onion with reddish-purple skin and flesh, milder and slightly sweeter than yellow onion when eaten raw, which is why it's the common choice raw in salads and salsas for both its color and gentler bite. Cooked, its color fades toward gray-purple and its flavor becomes closer to that of other cooked onions.
Buying guidance
Choose bulbs that are firm and heavy with dry, papery skin and no soft spots, sprouting, or a strong onion smell escaping through the skin, which signals a bulb already cut or bruised underneath. Size doesn't affect flavor much, so buy based on how much a dish needs rather than assuming a bigger bulb is milder.
Substitutions
- Shallot -- milder and sweeter still, good raw, but pale inside rather than purple.
- Yellow onion, thinly sliced and soaked in cold water for ten minutes -- mellows the sharper bite closer to red onion's raw mildness, though it adds no color.
- White onion -- sharper and more pungent raw than red onion, best when it'll be cooked rather than eaten raw.
Tips & common mistakes
Raw red onion's sharp bite can be noticeably mellowed by slicing it thin and soaking it briefly in cold water, or tossing it with a splash of vinegar or citrus juice and letting it sit for a few minutes, before adding it to something meant to be eaten raw.
Storage
Cut onion is one of the most potent odor-spreaders in a refrigerator -- store it in a well-sealed container rather than loosely wrapped, or it can noticeably flavor other food nearby, including things like butter or milk that easily pick up smells.