Onion
Onion is the aromatic backbone of more savory cooking traditions than almost any other ingredient. This page covers the everyday culinary onion in its common forms -- yellow, white, red, and sweet (Vidalia) -- which share the same basic flavor chemistry and are largely interchangeable, differing mainly in sharpness and sweetness.
How to buy
Choose onions that are firm with dry, papery, unbroken skin and no soft or wet spots. They should feel heavy for their size. Skip any with visible mold, sprouting green shoots, or a strong smell through the skin. Yellow onions are the all-purpose choice; red onions are sharper and best raw; Vidalia and other sweet onions are milder and best eaten raw or lightly cooked.
How to store
Keep whole onions in a cool, dark, well-ventilated spot -- a pantry basket or mesh bag, not a sealed plastic bag, which traps moisture and speeds rot. Store away from potatoes, which release moisture and gases that make onions spoil faster. Whole onions keep for several weeks to a couple of months at room temperature; don't refrigerate whole onions except in very hot, humid climates. Once cut, wrap tightly and refrigerate, using within about a week.
Culinary profile
- Flavor
- Pungent and sharp when raw, with a sulfurous bite that mellows and sweetens dramatically with cooking. Yellow onions are the balanced, all-purpose choice; red onions are sharper and more peppery raw; Vidalia and other sweet onions are mild and sugary even uncooked.
- Texture
- Crisp and crunchy raw. Softens quickly when sautéed, and turns silky, jammy, and almost spreadable after a long, slow caramelization.
- Aroma
- Raw onion's sharp, eye-watering smell comes from sulfur compounds released only once the cells are cut. Cooking breaks those compounds down, replacing the sharp smell with a sweet, nutty, almost caramel-like aroma as the onion browns.
How to prepare
- Diced — Cut into small, even cubes -- the standard starting point for soups, sauces, and sautés.
- Sliced — Cut into thin half-moons or rings for burgers, salads, stir-fries, or quick pickling.
- Caramelized — Cooked low and slow in fat for 30-45 minutes until deeply browned, sweet, and jammy.
- Quick-pickled — Thinly sliced and steeped in vinegar, salt, and a little sugar for a sharp, bright topping.
Classic dishes
American
- Philly cheesesteak — Thinly sliced beef and grilled onions on a hoagie roll with melted cheese.
- Classic diner burger — A beef patty topped with griddled or raw onion.
Italian
- Soffritto for ragù — Onion, carrot, and celery slowly softened in fat as the base for a long-simmered meat sauce.
Mexican
- Pico de gallo — A raw salsa of diced tomato, onion, chile, and lime.
- Cebollas encurtidas (pickled red onion) — Red onion quick-pickled with citrus and chile, a common taco topping.
Chinese
- Onion and beef stir-fry — Sliced onion stir-fried quickly with beef and a savory sauce, kept just past raw crunch.
Indian
- Onion bhaji — Sliced onions bound in spiced chickpea-flour batter and deep-fried into crisp fritters.
French
- French onion soup — Caramelized onions simmered in beef broth, topped with toasted bread and melted cheese.
- Caramelized onion and goat cheese tart — A savory tart showcasing slow-cooked onions on puff pastry or a tart shell.
Greek
- Horiatiki salad — A village salad of tomato, cucumber, olives, feta, and thinly sliced raw red onion.
Korean
- Bulgogi — Marinated, grilled beef served with softened onion from the same marinade.
Vietnamese
- Vietnamese pickled onion — A sharp, quick-pickled onion used to cut through rich grilled meats and noodle dishes.
Middle Eastern
- Stuffed onion dolma — Onions hollowed and filled with spiced rice and meat, then braised.
German
- Zwiebelkuchen (onion tart) — A savory custard tart loaded with softened onion and bacon.
Cajun & Creole
- Cajun holy trinity base — Onion, celery, and bell pepper sautéed together as the foundation for gumbo and jambalaya.
Caribbean
- Escovitch fish — Fried fish topped with a vinegary, spiced mix of pickled onion, carrot, and pepper.
British & Irish
- Liver and onions — Pan-fried liver served with softened, slightly sweet onions.
Substitutions
- Shallot — Milder and sweeter than onion; use roughly the same volume, but lean on it for lighter, quick-cooked or raw preparations rather than onion's long-cooked, heartier roles.