Why it works: Onion and mustard match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Pickled Onions
Ingredients
Directions
Make the brine
Boil the salt in water to make a brine.
Rub off the skins from the onions and add them to the brine.
Let the onions soak in the brine for 24 hours.
Pickle
Wipe the onions dry and place them in wide-mouthed bottles.
In a separate pot, boil the vinegar with peppercorns, mustard seed, and coriander seeds for 5 minutes.
Allow the mixture to cool, then pour it over the onions in the bottles.
Cork the bottles tightly and let them sit for 2 weeks before using.
Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.
Explore the science
The flavor team
The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.
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Onion + mustardtop 6% of all pairsSmell alikestrongCooked together9,259 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Vinegar + mustardtop 7% of all pairsSmell alikemoderateCooked together14,067 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Mustard + coriandertop 8% of all pairsSmell alikestrongCooked together967 recipes
Shared aroma: eucalyptol (eucalyptus, herbal).
-
Onion + coriandertop 11% of all pairsSmell alikemoderateCooked together8,219 recipes
Shared aroma: decanal (soap, orange peel).
-
Onion + vinegartop 14% of all pairsSmell alikemoderateCooked together18,226 recipes
Shared aroma: acetic acid (sour, vinegar).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Coarse sea salt
- Draws water out of the onions during the brine, firming them and seasoning them.
- White vinegar
- Provides the acidity that preserves the onions and gives the pickle its sharp flavor.
- Small silver skinned onions
- Form the body of the pickle, becoming tender and mild as they cure.
- Peppercorns
- Add pungent, aromatic heat that infuses into the vinegar.
- Mustard seed
- Adds a sharp, slightly pungent aroma and flavor to the vinegar.
The step that matters
Drying the onions before pickling. Any brine left on the onions dilutes the vinegar and can weaken preservation, so the onions should be wiped dry before they go into the bottles.
Swap the coriander
How well each one fits the dish's main ingredients (onion, vinegar, mustard):
- Capersfits better
- Garlicfits better
- Tarragonfits better
- Corianderthe original
Fit is the average pairing score against onion, vinegar, mustard. Candidates are from the same food group and used in at least 100 recipes.
“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.
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