Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and 68,474 recipes mention both. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Onion Soup for Six Persons
Ingredients
Directions
Prepare
Chop the six onions finely.
Fry the onions in a gallon saucepan with two ounces of butter or dripping fat, stirring continuously until they become very light in color.
Make the soup
Add six ounces of flour or oatmeal and moisten with three quarts of water.
Season with pepper and salt.
Stir the soup while boiling for twenty minutes.
Serve
When done, pour it into a pan or bowl containing slices of bread.
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. See the original page.
Explore the science
The flavor team
The pairs that carry this dish. Each one is judged two ways: how much aroma chemistry they share, and how many recipes mention both.
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Onion + peppertop 11% of all pairsAroma overlapmoderateMentioned together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Butter + flourtop 12% of all pairsAroma overlaplowMentioned together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Butter + oniontop 15% of all pairsAroma overlapmoderateMentioned together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Flour + oniontop 17% of all pairsAroma overlapmoderateMentioned together32,460 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Flour + peppertop 19% of all pairsAroma overlapmoderateMentioned together50,459 recipes
Shared aroma: isobutyraldehyde (malty, green).
Butter and flour share little aroma chemistry, yet 124,287 recipes mention both: they likely 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
- Onions
- Soften and sweeten as they fry gently, building the soup's base flavor.
- Butter
- Carries the onions' frying and adds richness to the soup.
- Flour
- Thickens the liquid as it boils, giving the soup body.
- Water
- Forms the liquid base that the flour thickens and the onions flavor.
The step that matters
Frying the onions. Onions cooked slowly and stirred constantly brown gradually, turning sweet and mellow. Rushing over high heat can scorch the sugars, leaving a bitter taste.
“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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