Out of Onion, one case

Onion substitutes for an onion allergy

4 options, ranked, with the exact amount

Use thisBest of 4 options

Use Fennel bulb

1 cup for every cup of onion

With an onion allergy, replace chopped onion with the same amount of chopped fennel bulb, or with half celery and half carrot, cooked the way the onion would have been. Neither is related to onion. Shallots, scallions, onion powder and onion salt are all onion. Leeks, chives and garlic are close relatives that some people with an onion allergy also react to, so ask your allergist before using them.

Verdict —: Tweak it
The tweak —: Trim the stalks and core, chop the bulb, and cook it in oil for 8 to 10 minutes until soft before adding other ingredients.
Best for —: soups, stews and braises

One casethe full onion card

Every option, one card

Ranked

Onion substitutes compared
#	Substitute	Instead of 1 cup onion	Verdict
1	Fennel bulbsoups, stews and braises	1 cupTweak it	Tweak it
2	Celery + carrotsoup, stock and stew	½ cup celery + ½ cup carrotYou'll taste it	You'll taste it
3	Asafoetida (hing)dals, curries and bean dishes	¼ tspYou'll taste it	You'll taste it
4	Bell pepperfajitas, stir-fries and skillet dishes	1 cupYou'll taste it	You'll taste it
Not a swap	Shallots, scallions and onion powder	not a swapNot for this	Not for this

What changesWhat changes, option by option4 options

Fennel bulb

sweet and mild, with a faint anise note

Fennel is in the carrot and celery family, not the onion family. Chopped and cooked in fat it softens, turns sweet and browns much as onion does, and most of its anise taste cooks away.

Best for: soups, stews and braises, pasta sauces and risotto, roasted or caramelized as a side
Prep: Trim the stalks and core, chop the bulb, and cook it in oil for 8 to 10 minutes until soft before adding other ingredients.
Where it fails: It has no onion bite. Dishes where raw onion is the point, such as pico de gallo, taste different.

Sliced thin and raw, it gives salads and sandwiches the crunch of raw onion with no sharpness.

Celery + carrot

savory and a little sweet, without onion flavor

The other two vegetables of a classic soup base, used without the onion. Celery brings the savory side and carrot brings the sweetness that cooked onion would have added.

Best for: soup, stock and stew, meat sauces and chili, stuffing and meatloaf
Prep: Dice both small and cook in fat until soft, about 8 minutes, as the recipe would have cooked the onion.
Where it fails: Celery is its own allergen. Skip it if you react to celery, and use fennel or more carrot.

Asafoetida (hing)

savory, like cooked onion and garlic

A pungent dried resin from a plant in the fennel family, used in Indian cooking that avoids onion and garlic. Fried briefly in oil, it gives a savory onion-and-garlic aroma.

Best for: dals, curries and bean dishes, soups and cooked sauces, adding onion-like aroma alongside fennel or celery
Prep: Fry it in the hot oil for a few seconds at the start of cooking. Start with a pinch if you have not used it before; raw, it smells harsh.
Where it fails: It adds aroma only, with no bulk, sweetness or texture. Never use it raw or sprinkle it on at the table.

Most jars are the resin blended with flour, often wheat flour. Read the label if you also avoid gluten.

Bell pepper

grassy or sweet pepper, not onion

Diced bell pepper fills the place of onion in a pan of sauteed vegetables and stays crisp when raw. Green pepper is the more savory; red is sweeter.

Best for: fajitas, stir-fries and skillet dishes, salsa, salads and sandwiches in place of raw onion, rice dishes, chili and Cajun cooking
Where it fails: Long-simmered dishes where the onion was meant to melt into the sauce; pepper keeps its own flavor.

Shallots, scallions and onion powder

onion

These are the usual onion substitutes, and they are onion. Shallots are a variety of onion, scallions are young onions, and onion powder, onion salt and dried minced onion are dried onion.

Best for: nothing with an onion allergy
Where it fails: All of them contain what you are avoiding. Do not count on cooking to change that; ask your allergist.

How it behaves in this recipe

In this recipeOnion

An onion allergy is different from avoiding onion for digestion. Advice written for a low-FODMAP diet, such as using onion-infused oil or the green tops of scallions, is aimed at the sugars in onion, not the proteins involved in an allergy. Do not rely on it for an allergy.

Tips for substituting onion

5 tips

For a cooked base, replace 1 cup chopped onion (1 medium onion) with 1 cup chopped fennel bulb, or ½ cup each of diced celery and carrot. Cook it in fat until soft before going on with the recipe.
For raw crunch on a burger, taco or salad, use thin-sliced fennel, diced bell pepper or radish.
Read the full ingredient list on broth, bouillon, soup mixes, spice blends, sausages, sauces, ketchup and salad dressings. Onion is not one of the major allergens that US labels must call out separately.
Make your own stock and seasoning blends. A stock of carrot, celery, parsley stems, peppercorns and bay leaf needs no onion.
When eating out, say "onion allergy" and name the hidden forms: onion powder, stock, gravy and marinades.

Questions

5 questions

Can I use garlic, leeks or chives if I am allergic to onion?

Not without checking. Garlic, leeks and chives belong to the same plant family as onion, and some people with an onion allergy react to them as well. Ask your allergist which ones are safe for you before cooking with them.

Is onion powder safe if I am allergic to onion?

No. Onion powder, onion salt, dried minced onion and granulated onion are all dried onion. Shallots and scallions are onions too.

Can I use onion-infused oil?

Do not assume so. Onion-infused oil is a low-FODMAP technique for people who digest onion poorly. It is not advice for an allergy. Ask your allergist.

What replaces onion in soup?

Use 1 cup of chopped fennel bulb, or ½ cup each of celery and carrot, for each medium onion, and cook it in oil or butter until soft before adding the liquid. A pinch of asafoetida fried in the oil adds an onion-like aroma.

What replaces raw onion in salads and salsa?

Thin-sliced fennel, diced bell pepper, radish or cucumber give the crunch. None has the sharp bite of raw onion, so add a little extra lime juice or vinegar and salt.