Why it works: Tomato and pepper are a kitchen classic. They rank in the top 7% of all ingredient pairs, and 17,923 recipes mention both. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Tomato Soup
Ingredients
Directions
Prepare
Wash and slice the tomatoes, then place them in an enamel bowl.
Add pepper, salt, baking soda, hot water, and chopped onion.
Cook and strain
Boil until very soft.
Rub the mixture through a fine sieve.
Finish
Add the strained liquid and sugar.
Bring to a boil.
Stir in the undiluted milk, then do not boil again to prevent curdling.
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 aroma chemistry they share, and how many recipes mention both.
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Tomato + peppertop 7% of all pairsAroma overlapmoderateMentioned together17,923 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Tomato + oniontop 8% of all pairsAroma overlapmoderateMentioned together20,633 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Pepper + oniontop 11% of all pairsAroma overlapmoderateMentioned together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Tomato + milktop 15% of all pairsAroma overlapmoderateMentioned together2,226 recipes
Shared aroma: 1-octen-3-one (mushroom, metallic).
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Sugar + milktop 18% of all pairsAroma overlaplowMentioned together77,875 recipes
Shared aroma: 2-nonenal (fatty, green).
Sugar and milk share little aroma chemistry, yet 77,875 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
- Ripe tomatoes
- Form the soup's main body, providing moisture, acidity and most of the flavour.
- Baking soda
- Neutralises some of the tomatoes' acid and helps them soften and break down faster.
- Onion
- Adds a savoury aromatic base that rounds out the tomato flavour.
- Sugar
- Balances the tomatoes' sharp acidity with a touch of sweetness.
- Undiluted milk
- Adds richness and creaminess, giving the soup a smooth, mellow body.
The step that matters
Stir in the milk without boiling again. Milk proteins are prone to curdling when heated in an acidic tomato base. Keeping the soup below a boil after the milk goes in keeps it smooth instead of grainy and separated.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (tomato, pepper, sugar, milk):
- Capsicumbetter flavor fit
- Potatobetter flavor fit
- Carrotbetter flavor fit
- Onionthe original
Fit is the average pairing score against tomato, pepper, sugar, milk. Candidates are from the same food group and used in at least 100 recipes. This compares flavor only: it does not check the job the ingredient does in the dish (bulk, moisture, acidity, structure).
“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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