Few ingredients are as foundational to savory cooking as the onion. Whether slowly caramelized into deep sweetness, sweated gently into the base of a soup, or sliced raw for sharp contrast and crunch, onions shape the flavor architecture of cuisines around the world.
Part of the allium family alongside garlic, shallots, leeks, and chives, onions are valued for their ability to transform dramatically depending on how they are prepared. Raw onions are pungent, sulfurous, grassy, and sharp. With heat, those aggressive compounds soften into sweetness, savoriness, and rich aromatic depth.
While many varieties exist—including yellow, white, red, sweet, pearl, and cipollini onions—the yellow onion is generally considered the standard all-purpose cooking onion in Western kitchens.
Raw onions are sharp, sulfurous, grassy, and aggressively aromatic with a lingering pungency that can range from mildly peppery to eye-wateringly intense depending on the variety and freshness.
As onions cook, their flavor changes dramatically. Gentle heat softens their bite while drawing out natural sugars, creating savory sweetness and rich aromatic depth.
Raw onions are crisp, juicy, and layered, offering both crunch and moisture depending on the cut.
As onions cook, their texture softens considerably. Sweated onions become silky and tender, while slowly caramelized onions collapse into jammy strands with deep sweetness.
Onions serve as one of the most important aromatic foundations in savory cooking. They are frequently combined with ingredients like celery, carrots, peppers, garlic, or ginger to create flavor bases that support soups, stews, sauces, braises, curries, stir-fries, stocks, and roasted dishes.
They may be used raw for crunch and sharpness, lightly cooked for sweetness and body, or deeply caramelized for richness and complexity.
Trim the root and stem ends, then peel away the papery outer skin to expose the firm, layered flesh beneath. Depending on the dish, onions can be sliced into thin half-moons, diced for even distribution, minced for a finer texture, or cut into wedges for heartier preparations. The way the onion is cut directly affects both texture and how its flavor develops during cooking.
When working with onions, the natural sulfur compounds released during cutting can cause tearing. To minimize this, chill the onion beforehand or rinse it briefly under cold water, which helps slow the release of those compounds. Using a sharp knife and working efficiently can also make a noticeable difference.
Remove any soft, bruised, sprouted, or discolored layers before use.
For diced onion, make horizontal and vertical cuts before slicing downward across the grain.
Cutting onions releases sulfur compounds that may irritate the eyes and cause tearing.
Store whole onions in a cool, dry, well-ventilated place away from direct sunlight. Avoid sealed plastic bags, which trap moisture and encourage spoilage.
IMPORTANT: Keep onions separate from potatoes, which can shorten their storage life. Once cut, refrigerate in an airtight container.
Onions can be frozen raw or cooked, but freezing softens their texture. Frozen onions are best used in cooked dishes like soups, stews, sauces, casseroles, and sautés rather than raw applications. Dice or slice before freezing, spread on a tray until firm, then transfer to a freezer-safe bag or container.
Whole onions can last several weeks to months depending on the variety and storage conditions. Cut onions should typically be used within several days when refrigerated properly.
Discard onions that feel soft, slimy, moldy, heavily sprouted, or emit sour or fermented odors.
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Nutrition Facts
Servings per container: ; Serving size: 100 g (100g)
Amount per serving:
Calories 40, Total Fat 0.1g, Saturated Fat 0.0g, Trans Fat 0g, Cholesterol 0mg, Sodium 4mg, Total Carbohydrate 9.3g, Dietary Fiber 1.7g, Total Sugars 4.2g, Protein 1.1g, Vitamin D 0mcg, Calcium 23mg, Iron 0.2mg, Potassium 146mg.
More nutrition
Polyunsaturated Fat 0.0g, Monounsaturated Fat 0.0g, Soluble Fiber not listed, Insoluble Fiber not listed, Sugar Alcohols not listed, Net Carbs 7.6g, Vitamin A 0mcg RAE, Vitamin C 7.4mg, Vitamin E 0.0mg, Vitamin K 0.4mcg, Thiamin (B1) 0.0mg, Riboflavin (B2) 0.0mg, Niacin (B3) 0.1mg, Vitamin B6 0.1mg, Folate 19mcg DFE, Folic Acid 19mcg, Vitamin B12 0mcg, Pantothenic Acid 0.1mg, Phosphorus 29mg, Magnesium 10mg, Zinc 0.2mg, Selenium 0.5mcg, Copper 0.0mg, Manganese 0.1mg, Caffeine 0mg, Alcohol 0g, Water 89.1g.
Nutrition information is estimated using USDA FoodData Central and other reference sources. Actual values may vary based on ingredient variety, preparation method, brand, ripeness, processing, and measurement accuracy.
