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
Make the base
Stew the tomatoes in 1 quart of water for 2 hours with the chopped onions.
Fry the onions until nicely brown.
Pass the mixture through a wire sieve.
Thicken and season
Thicken the soup with ½ cup of wholemeal flour, stirred into cold water.
Add pepper, coarse sea salt, and mixed herbs.
Boil for 20 minutes.
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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Onion + peppertop 11% of all pairsAroma overlapmoderateMentioned together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Onion + flourtop 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).
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, acidity and fresh flavour of the soup.
- Spanish onions
- Browned by frying, they add savoury sweetness and deeper colour to the soup.
- Wholemeal flour
- Its starch swells as the liquid heats, thickening the soup.
The step that matters
Stirring the flour into cold water before adding it. Flour stirred into cold water disperses evenly, so its starch thickens the soup smoothly. Flour added dry or to hot liquid clumps into lumps that are hard to remove.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (tomato, flour, pepper):
- Capsicumbetter flavor fit
- Okrabetter flavor fit
- Eggplantbetter flavor fit
- Onionthe original
Fit is the average pairing score against tomato, flour, pepper. 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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