Why it works: Onion and tomato are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 20,633 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Tomato Soup
Ingredients
Directions
Make the soup
Melt butter in a pot.
Sauté the onion until soft.
Add the tomato, bay leaf, water, cloves, and salt.
Cook for 20 minutes.
Thicken and finish
Mix flour with an equal amount of water until smooth.
Add more water until thin enough to pour.
Gradually stir the flour mixture into the soup.
Boil for 5 minutes.
Strain the soup.
Add sugar.
Serve 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.
Photo for illustrative purposes only · Contact us to use it
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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Onion + tomatotop 8% of all pairsSmell alikemoderateCooked together20,633 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Tomato + clovetop 12% of all pairsSmell alikemoderateCooked together3,474 recipes
Shared aroma: ethyl caproate (fruity, apple peel).
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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Onion + clovetop 13% of all pairsSmell alikemoderateCooked together16,901 recipes
Shared aroma: 2-nonanone (fruity, floral).
-
Flour + sugartop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
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
- Butter
- Adds fat and richness, and helps carry flavour from the aromatics.
- Flour
- Thickens the soup as its starch swells when stirred into the hot liquid.
- Tomato
- Forms the base of the soup and provides its main flavour and acidity.
- Onion
- Softens while cooking to add savoury aroma and sweetness to the base.
- Sugar
- Balances the acidity of the tomato for a rounder taste.
The step that matters
Gradually stir the flour mixture into the soup. Adding the flour slowly while stirring prevents lumps, because starch clumps when it hits hot liquid all at once. Keep the soup moving so the starch disperses and thickens evenly.
Swap the tomato
How well each one fits the dish's main ingredients (onion, butter, flour, clove, sugar):
- Leekfits better
- Shallotfits better
- Chivefits better
- Tomatothe original
Fit is the average pairing score against onion, butter, flour, clove, sugar. 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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