Why it works: Butter and cream are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 41,516 recipes. Both carry delta-dodecalactone, which smells sweet, creamy. The science ↓
Onion Sauce
Ingredients
Directions
Prepare the onions
Peel and cut the onions in half.
Soak them in spring water for 15 minutes.
Boil the onions until tender, about 1 hour.
Drain the onions and chop them finely.
Make the sauce
In a clean saucepan, combine the chopped onions with butter and flour.
Add salt and cream or milk, stirring until it boils.
Rub the mixture through a sieve, adding more milk or cream for desired consistency.
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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Butter + creamtop 8% of all pairsSmell alikemoderateCooked together41,516 recipes
Shared aroma: delta-dodecalactone (sweet, creamy).
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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Onion + flourtop 17% of all pairsSmell alikemoderateCooked together32,460 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Onion + creamtop 18% of all pairsSmell alikelowCooked together10,827 recipes
Shared aroma: 2-nonanone (fruity, floral).
Butter and flour barely smell alike, yet cooks put them together in 124,287 recipes: they work on texture and structure more than aroma.
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- White onions
- Provide the main body and sweet flavour of the sauce once cooked soft and pureed.
- Butter
- Adds richness and fat, carrying flavour and giving the sauce a smooth mouthfeel.
- Flour
- Thickens the sauce as it heats, giving it body and a smooth, cohesive texture.
- Cream or milk
- Adds moisture and creaminess, and sets the final consistency of the sauce.
The step that matters
Rub the mixture through a sieve. Onion fibres must be pushed fully through the sieve to get a smooth sauce. Thinning with milk or cream only after straining lets you correct the texture without making it watery.
Swap the onion
How well each one fits the dish's main ingredients (butter, flour, cream):
- Leekfits better
- Arrowrootfits better
- Chivefits better
- Onionthe original
Fit is the average pairing score against butter, flour, cream. 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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