Why it works: Butter and bread are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 27,232 recipes. Both carry delta-decalactone, which smells sweet, creamy. The science ↓
Onion Soup
Ingredients
Directions
Make the soup
In a pan, melt the butter and fry the onions until tender but not brown.
Pour in the stock and add salt and cayenne pepper.
Simmer for 15 minutes, then press the soup through a sieve.
Finish and serve
Return the soup to the saucepan and stir in the bread crumbs and hot cream.
Taste for seasoning and serve with small slices of toast.
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 + breadtop 7% of all pairsSmell alikemoderateCooked together27,232 recipes
Shared aroma: delta-decalactone (sweet, creamy).
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Butter + creamtop 8% of all pairsSmell alikemoderateCooked together41,516 recipes
Shared aroma: delta-dodecalactone (sweet, creamy).
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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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Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Onion + breadtop 15% of all pairsSmell alikemoderateCooked together8,676 recipes
Shared aroma: 2,4-decadienal (seaweed).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Onions
- Soften and sweeten as they cook gently in butter, forming the soup's main flavour base.
- Butter
- Carries the onions' flavour and adds richness while frying them gently.
- Stock
- Forms the liquid base that the onions simmer in and that gives the soup its body.
- Bread crumbs
- Thicken the soup slightly as they absorb liquid during simmering and reheating.
- Cream
- Adds richness and a smooth, silky mouthfeel to the finished soup.
The step that matters
Frying the onions until tender but not brown. Browning the onions adds bitter, caramelised notes that change the soup's flavour, so they should soften gently over moderate heat until tender without colouring.
Swap the onion
How well each one fits the dish's main ingredients (butter, pepper, bread, cream):
- Potatofits about as well
- Capsicumfits about as well
- Spinachfits about as well
- Onionthe original
Fit is the average pairing score against butter, pepper, bread, 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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