Photo by Scot Nelson on Wikimedia Commons (CC0 1.0)

onion

ProducePeak season varies by region and harvest timing; in the Northern Hemisphere, onions are harvested June through September, with storage extending availability year-round. Certain regions practice spring harvesting of green/scallion onions, while mature bulbs remain available throughout the year in most markets.

Onions are a good source of vitamin C, dietary fiber, and prebiotic compounds (inulin). They contain quercetin and other polyphenolic antioxidants, particularly concentrated in the outer layers and red varieties.

About

The onion (Allium cepa) is a bulbous vegetable belonging to the amaryllidaceae family, native to the highlands of Central Asia. The edible bulb consists of concentric layers of modified leaves containing sulfurous compounds responsible for the characteristic pungent aroma and tear-inducing properties when cut. Common varieties include yellow (sweet and mellow), red (slightly sweeter with mild peppery notes), and white onions (sharper, more pungent), each offering distinct flavor profiles and textural qualities. The plant's flavor compounds transform dramatically with cooking—sulphur-containing compounds break down into sweet, caramelized notes through the Maillard reaction.

Yellow onions are the most versatile all-purpose variety in European and North American cuisines, while red onions are preferred for raw preparations due to their milder flavor and visual appeal. Pearl onions and cipollini represent smaller, sweeter cultivars used for specific applications.

Culinary Uses

Onions function as a foundational aromatic base in countless cuisines worldwide. They are sautéed as a primary component in mirepoix (French), soffritto (Italian), and holy trinity preparations (Louisiana Creole), forming the flavor foundation for stocks, soups, stews, and sauces. Caramelized onions develop deep, sweet complexity through prolonged cooking and appear in French onion soup, as a burger topping, and in numerous savory tarts.

Raw onions provide sharp, pungent flavor to fresh salsas, slaws, pickles, and salads. Grilled or roasted onions become tender and develop subtle sweetness, complementing grilled meats and vegetables. Creamed onions, onion relishes, and crispy fried onions represent further preparations across global culinary traditions.

Forms & Preparations

Raw/sliced — Thin-sliced or diced for use in salads, salsas, and raw preparations; sharper flavor and crisp texture.
Whole/unpeeled — Roasted whole in skin until caramelized, then flesh squeezed from papery exterior for a sweet, mild base or accompaniment.
Raw sliced or diced — Thinly sliced or chopped for use in fresh applications including salads, salsas, and garnishes, providing sharp pungent flavor
Raw, sliced or diced — Thin slices or uniform dice for salads, salsas, ceviche, and raw garnishes; delivers sharp, pungent flavor.
Whole bulb (raw or cooked) — Used intact for roasting, braising, or grilling; also halved or quartered for stocks and long-simmered dishes.
Whole bulb — Unpeeled onion used for caramelizing, roasting, or charring; develops sweetness through application of dry or moist heat.
Whole/Raw — Fresh bulbs used sliced or chopped raw in salads, salsas, and garnishes for sharp, crisp bite.
Diced or chopped — Irregular or uniform pieces ranging from rough chop to fine mince; standard form for sautéing, sweating, and building flavor bases.
Caramelized — Slowly cooked over extended time until deeply browned and sweet, used as a condiment or component in soups and composed dishes
Diced — Cut into roughly 1/4-inch cubes, the standard form for mirepoix, soffritto, and building flavor bases in soups and stews.
Diced/Minced — Small uniform cuts for quick cooking as an aromatic base in sauces, soups, and stir-fries.
Julienned — Thin matchsticks for raw salads, Asian stir-fries, and as an elegant garnish.
Sautéed/softened — Quickly cooked in fat until translucent; standard aromatics base for soups, stews, and sauces.
Sliced/Rings — Thin or thick cuts for caramelizing, grilling, frying, or layering in gratins and sandwiches.
Roasted or grilled — Halved or quartered bulbs roasted whole or cut, developing mild sweetness and tender texture
Sliced — Cut crosswise into rings or half-moons, used for caramelizing, raw salads, or quick-cooking in stir-fries.
Julienned/matchstick — Cut into thin, uniform sticks for faster cooking, fine texture in stir-fries, or delicate raw applications.
Wedges/Quarters — Cut into large chunks for roasting whole, grilling, or slow-braising where texture and shape should be maintained.
Julienned or matchstick — Thin, uniform strips; for quick sautéing, stir-fries, or raw garnish where texture and visual appeal matter.
Roasted — Whole or halved bulbs roasted at high heat until tender and caramelized; served as a side dish or incorporated into composed dishes.
Whole or halved — Left intact or split lengthwise; used for roasting, stuffing, or as part of a braising aromatics bundle.
Minced or finely chopped — Reduced to small pieces for salsas, relishes, and raw applications where subtle texture and quick incorporation are desired.
Whole/Quartered — Left intact or cut into large pieces for roasting, grilling, or adding to stocks without breaking down.
Pickled — Preserved in vinegar-based brine with spices, ranging from quick-pickled (hours) to fermented preparations
Roasted/Grilled Whole — Unpeeled bulbs or halves cooked until tender and golden, served as a side dish or component.
Minced — Finely chopped, used for salsas, dressings, and dishes requiring even, quick incorporation of onion flavor.
Dehydrated or powdered — Dried and ground into fine powder, used as a seasoning and flavoring agent in spice blends and dry rubs
Caramelized paste or confit — Reduced to a concentrated, spreadable consistency; used in sauces, sandwiches, or as a base for soups.
Powder — Dried and ground onion, used as a seasoning in spice blends, dry rubs, and soups where fresh onion is impractical; 1 tablespoon powder ≈ 1 medium fresh onion.
Powdered — Dried and ground into fine powder for spice blends and dry rubs
Powder/Dehydrated — Dried and ground onion used as a seasoning in spice blends, rubs, and instant soups.
Roasted/Grilled — Whole bulbs roasted until soft and sweet or halved and grilled with char; served as a side dish or incorporated into purées and dips.
Powder or dried flakes — Dehydrated and ground for seasoning blends, dry rubs, and convenience in applications where fresh onion is impractical.
Fried or crisped — Thinly sliced and deep-fried until golden and brittle, used as a garnish or textural element in various cuisines
Powder/dehydrated — Dried and ground into fine particles; used as seasoning in dry rubs, spice blends, and instant flavoring.