Onion

Taste and Texture

Raw onions have a sharp aroma, a light heat, and a crisp, moisture-rich texture. The thinner you slice, the more immediately the pungent scent is perceived; thicker slices leave a more pronounced chewing feel and sweetness. When heated, the tissue softens and the sharp aroma fades. Slow-cooking onions over low heat yields sweetness and softness, while heating on high heat for too long can cause the outer edges to darken, making bitterness more noticeable than sweetness.

Main uses

• For broths, stews, curry, and braises, start by sautéing onions to form a base of sweetness and aroma. Once translucent, add water or stock so the onion aroma spreads relatively evenly through the liquid.
• In fried rice, chow mein, or stir-fried vegetables, add onions first to shed some moisture; if the pan is very wet, the dish will feel more stewing than sautéing, so adjust amounts or heat.
• For marinated meat dishes like bulgogi or spicy pork, add sliced onions to impart sweetness and moistened texture. If you don’t want them to become completely soft too early, add them after the meat has cooked to some extent.
• For salads, sandwiches, and bibimbap, use thinly sliced raw onions to add crunch and pungency. If the strong aroma feels heavy, briefly soak in cold water and pat dry.

Preparation tips

• For sautéing or broth use, split the root end in half lengthwise and cut to keep pieces relatively even. Uneven pieces cause smaller bits to burn while larger ones stay underdone, so adjust thickness by purpose.
• If you want caramelized, deep sautéed onions, spread them in a wide pan not too thick and stir frequently over medium-low heat. If the bottom sticks and browns, scrape with a small amount of water or stock and mix; adding too much water at once slows the sautéing process.
• When using raw, rinse off or soak sliced onions in cold water briefly to mellow the pungent aroma. However, soaking too long can lessen the onion’s aroma and sweetness, so for salads where the onion flavor is central, processing briefly is better.
• Excess moisture from onion slices can make sautéed dishes soggy. Don’t leave sliced onions sitting too long—prepare what you need and add to a hot pan, ensuring the pan is well heated.

Cooking characteristics

• Onions release moisture early in cooking, so if the pan is crowded they tend to steam rather than brown; use a wide pan or cook in batches if you want browning flavor.
• Slow cooking over medium-low heat makes the tissue soft, the sweetness more pronounced, and the color shifts from pale gold to brown. If the color darkens quickly and the aroma becomes bitter, the heat is likely too high; lower the flame and loosen the browned bits.
• Onions simmered in broth largely dissolve and contribute sweetness and body to the broth. For hot pots or braises where onion pieces are desired, avoid adding them too early.
• Using acidity like vinegar, lemon juice, or tomato with onions can make their sweetness stand out further. Conversely, adding strong acidity early can let a tangy taste outshine the nutty aroma of sautéed onions, so adding at the end can be appropriate depending on the dish.

Good combinations

• When used with garlic, green onions, and ginger, the flavor base becomes solid and suits soups and sautés; however, long sautéing of all aromatics can impart bitterness, so small ingredients like garlic should be added after the onions have softened to a point.
• Beef, pork, and chicken pair well with the sweetness of onions balancing salty seasonings. If the flavor is already strongly sweet, it is better to leave onions large to maintain texture instead of letting them wilt too much.
• Pairs well with salty, rich ingredients like soy sauce, miso, butter, and cheese; acids from vinegar or citrus help calm the sharpness of raw onions. However, in delicate white fish dishes, the onion aroma can overwhelm the ingredients, so reducing the amount or using lightly cooked onions is preferable.

Points to consider when substituting

• If you’re using onions mainly for broth or sauté base sweetness and aroma, you can substitute the white part of scallions or shallots. Scallions have a stronger aroma, shallots taste more delicate, so adjust seasonings rather than swapping exact quantities.
• For salads or sandwiches needing raw crisp onions, red onions, shallots, or finely sliced green onions can be alternatives. To reduce sharpness, you can mix in cucumber or other watery vegetables, but that does not replace the unique onion flavor.
• In dishes that require long sautéing for deep sweetness, substitutes can yield very different results. Green onions soften relatively quickly and carry a different flavor, so completely replicating the base onion in sauces or curries may not be suitable.