Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓
Onion and Cucumber Soup
Ingredients
Directions
Make the vegetable base
In a pan, melt 1 tablespoon of butter over medium heat.
Add the chopped onions and cucumbers, and fry for 5 minutes without browning.
Pour in 1 pint of boiling water and simmer for 45 minutes.
Press the mixture through a sieve to extract as much pulp as possible.
Make the thickened milk and finish
In another saucepan, melt 1 tablespoon of butter and stir in 1 tablespoon of flour.
Gradually add 1 pint of hot milk, stirring until smoothly thickened.
Mix the thickened milk with the cucumber puree, season with salt and pepper, and simmer for 5 minutes.
Serve hot with croutons.
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 + milktop 7% of all pairsSmell alikemoderateCooked together81,283 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Onion + cucumbertop 8% of all pairsSmell alikestrongCooked together6,050 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Cucumber + peppertop 12% of all pairsSmell alikemoderateCooked together5,991 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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
- Softened in butter to build the soup's savoury, sweet base flavour.
- Cucumbers
- Provide the main vegetable body and fresh flavour once simmered and pureed.
- Flour
- Thickens the butter and milk mixture into a smooth, body-giving sauce.
- Milk
- Adds creaminess and richness, and with the flour forms a smooth thickened base.
The step that matters
Stirring in the milk gradually. Adding hot milk slowly to the butter and flour roux, while stirring, keeps lumps from forming so the thickening stays smooth.
Swap the cucumber
How well each one fits the dish's main ingredients (onion, butter, flour, milk, pepper):
- Potatofits better
- Chivefits better
- Leekfits better
- Cucumberthe original
Fit is the average pairing score against onion, butter, flour, milk, pepper. 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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