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 quarter the onions if large.
Soak the onions in spring water for 15 minutes.
Boil the onions in fresh water for 15 minutes.
Drain the onions.
Cover with fresh boiling water and boil until tender.
Drain the onions through a sieve.
Chop the onions finely.
Rub the onions through a coarse sieve or fine colander.
Make the sauce
Mix flour and butter in a clean saucepan over heat.
Once the butter is melted, add the onions, cream, salt, and white pepper.
Stir until hot, adding more cream or milk if needed.
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
- Spanish onions
- Form the bulk of the sauce and, once rubbed smooth, give it its body and flavour.
- Butter
- Enriches the sauce and carries flavour, and with the flour forms the base for thickening.
- Flour
- Cooked with the butter to thicken the sauce and give it body.
- Cream
- Adds richness and a smooth, silky texture to the sauce.
The step that matters
Rub the onions through a sieve. Pushing cooked onion through a sieve breaks down its fibres and removes lumps, which gives the sauce a smooth texture. Chopping alone leaves pieces that stay coarse.
Swap the white pepper
How well each one fits the dish's main ingredients (onion, butter, flour, cream):
- Garlicfits better
- Capersfits better
- Nutmegfits better
- White pepperthe original
Fit is the average pairing score against onion, 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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