Why it works: Tomato and pepper are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 17,923 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Red Sauce
Ingredients
Directions
Prepare
Scald and peel the tomatoes.
Peel and chop the onions. Chop the red peppers.
Cook and bottle
In a large pot, combine the tomatoes, onions, red peppers, salt, sugar, and vinegar. Boil for 1 hour.
Bottle and seal the sauce.
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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Tomato + peppertop 7% of all pairsSmell alikemoderateCooked together17,923 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Tomato + oniontop 8% of all pairsSmell alikemoderateCooked together20,633 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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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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Onion + vinegartop 14% of all pairsSmell alikemoderateCooked together18,226 recipes
Shared aroma: acetic acid (sour, vinegar).
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Pepper + vinegartop 14% of all pairsSmell alikemoderateCooked together27,814 recipes
Shared aroma: 4'-methylacetophenone (bitter almond).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Tomatoes
- Form the bulk of the sauce and give it body and moisture as they break down.
- Onions
- Add savoury depth and aroma that builds during the long boil.
- Red peppers
- Contribute sweetness, colour and a mild fresh flavour to the sauce.
- Sugar
- Adds sweetness that balances the sharpness of the vinegar.
- Vinegar
- Adds acidity that sharpens the flavour and helps preserve the sauce.
The step that matters
Boil for 1 hour. A long, steady boil softens the tomatoes and peppers, breaks down their structure and evaporates water, so the sauce thickens and the flavours blend.
Swap the onion
How well each one fits the dish's main ingredients (tomato, pepper, sugar, vinegar):
- Capsicumfits better
- Cucumberfits better
- Mustardfits better
- Onionthe original
Fit is the average pairing score against tomato, pepper, sugar, vinegar. 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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