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 ↓
Home Made French Mustard
Ingredients
Directions
Prepare the onion
Slice the onion.
Cover the onion with vinegar.
Let it soak for two days.
Pour off the vinegar.
Make the mustard
Add salt, sugar and cayenne pepper.
Add enough mustard powder to thicken.
Heat the mixture on the stove until it boils, stirring well.
Remove from heat.
Bottle the mustard.
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).
-
Pepper + mustardtop 9% of all pairsSmell alikemoderateCooked together15,430 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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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
- Onion
- Soaking in vinegar softens and mellows its sharp flavour before it is blended into the mustard.
- Vinegar
- Provides the acidity that gives the mustard its sharp, tangy taste.
- Mustard powder
- Thickens the mixture and supplies the characteristic mustard flavour.
The step that matters
Heating until it boils. Heating the mixture until it boils cooks the thickening powder so the mustard sets properly, and stirring keeps it smooth and prevents lumps or scorching on the bottom of the pan.
Swap the onion
How well each one fits the dish's main ingredients (vinegar, sugar, pepper, mustard):
- Horseradishfits better
- Capsicumfits better
- Radishfits better
- Onionthe original
Fit is the average pairing score against vinegar, sugar, pepper, 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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