Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and 81,283 recipes mention both. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓
Tomato Soup
Ingredients
Directions
Combine cold water, tomatoes, and sliced onion in a pot.
Boil for nearly an hour.
Strain the mixture and add baking soda. Stir until it stops foaming.
Add butter, sweet milk, and rolled crackers. Bring to a boil and serve.
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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Butter + milktop 7% of all pairsAroma overlapmoderateMentioned together81,283 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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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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Onion + buttertop 15% of all pairsAroma overlapmoderateMentioned together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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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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Butter + eggtop 17% of all pairsAroma overlapmoderateMentioned together118,967 recipes
Shared aroma: decanal (soap, orange peel).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Tomatoes
- Provide the main body and tangy flavor of the soup as they cook down.
- Baking soda
- Neutralizes the tomato acidity, reducing sourness and causing foaming when added.
- Sweet milk
- Adds creaminess and mild sweetness, softening the tomato's acidity.
- Rolled crackers
- Thicken the soup slightly as they absorb liquid and soften.
- Butter
- Adds richness and a smooth, rounded mouthfeel to the soup.
The step that matters
Adding baking soda to the strained tomato mixture. Baking soda reacts with the tomato acids and releases carbon dioxide, so it foams vigorously. Add it slowly and let the foaming subside before adding dairy, otherwise the soup may boil over and the milk can curdle when acidity is unevenly neutralized.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (tomato, butter, egg, milk):
- Potatobetter flavor fit
- Capsicumbetter flavor fit
- Asparagusbetter flavor fit
- Onionthe original
Fit is the average pairing score against tomato, butter, egg, 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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