Why it works: Celery and pepper match in chemistry and in kitchens. They rank in the top 5% of all ingredient pairs, and cooks put them together in 16,012 recipes. Both carry 4'-methylacetophenone, which smells bitter almond. The science ↓
Onion Soup
Ingredients
Directions
Make the stock
Chop the bones and fat into small pieces. Place them in a large pot with 1 gallon of cold water. Boil for 1 hour.
Add the vegetables
Peel the onions and trim the celery. Place them in a net and add them with the remaining water to the pot. Boil for 40 minutes (longer if onions are very large).
Finish the soup
Remove the onions and celery, then pulp them. Return the pulp to the pot with the seasoning and flour mixed in. Boil for an additional 30 minutes.
Serve
Cut the bread into dice. Place it in a bowl, and pour the soup over it. Serve hot.
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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Celery + peppertop 5% of all pairsSmell alikestrongCooked together16,012 recipes
Shared aroma: 4'-methylacetophenone (bitter almond).
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Onion + celerytop 7% of all pairsSmell alikemoderateCooked together18,518 recipes
Shared aroma: guaiacol (smoky, sweet).
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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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Sugar + flourtop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
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Celery + flourtop 15% of all pairsSmell alikemoderateCooked together6,905 recipes
Shared aroma: isobutyraldehyde (malty, green).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Onions
- Break down into the pulp that gives the soup body and a deep, sweet flavor.
- Fat and bones
- Release fat and gelatin into the water, adding richness and body to the broth.
- Flour
- Thickens the pulped broth as its starch swells in the hot liquid.
- Bread
- Soaks up the hot broth, softening and becoming part of the dish.
- Sugar
- Adds sweetness that balances the savory broth and the salt.
- Celery
- Adds a fresh, aromatic background flavor to the broth.
The step that matters
Return the pulp to the pot with the flour mixed in. Flour that goes into hot liquid unmixed clumps as its outer starch swells before the rest can wet. Mixing it with the seasoning first spreads it evenly, so the soup thickens smoothly.
Swap the onion
How well each one fits the dish's main ingredients (sugar, celery, pepper, flour, bread):
- Carrotfits better
- Capsicumfits better
- Mustardfits better
- Onionthe original
Fit is the average pairing score against sugar, celery, pepper, flour, bread. 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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