Why it works: Tomato and pepper match in chemistry and in kitchens. They rank in the top 4% of all ingredient pairs, and 17,913 recipes mention both. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
The recipe
Ingredients
Directions
Chop 25 ripe peeled tomatoes finely.
Chop 4 onions finely.
Chop 8 peppers, seeds removed, finely.
Combine tomatoes, onions, peppers, 8 cups vinegar, 4 tablespoonfuls sugar, 2 tablespoonfuls salt.
Boil gently for one hour.
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. See the original page.
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 4% of all pairsAroma overlapstrongMentioned together17,913 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Tomato + oniontop 4% of all pairsAroma overlapstrongMentioned together20,622 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Onion + peppertop 6% of all pairsAroma overlapmoderateMentioned together68,463 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Sugar + peppertop 22% of all pairsAroma overlaplowMentioned together19,398 recipes
Shared aroma: 2-nonenal (fatty, green).
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Sugar + tomatotop 22% of all pairsAroma overlaplowMentioned together4,683 recipes
Shared aroma: beta-damascenone (apple, rose).
Sugar and pepper share little aroma chemistry, yet 19,398 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
- Tomatoes
- Provide the main bulk and moisture that cook down into the relish's body.
- Onions
- Add sharp aroma that mellows and becomes sweeter during long cooking.
- Peppers
- Contribute fresh, slightly bitter flavor and some texture to the relish.
- Vinegar (in the method)
- Adds acidity that gives the relish its tang and helps preserve it.
- Sugar
- Adds sweetness that balances the sharpness of the vinegar.
The step that matters
Boil gently for one hour.. A gentle simmer lets water evaporate slowly so the relish thickens and the vegetables soften evenly. Boiling too hard can scorch the bottom and break up the pieces unevenly.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (sugar, tomato, pepper):
- Capsicumbetter flavor fit
- Carrotbetter flavor fit
- Potatobetter flavor fit
- Onionthe original
Fit is the average pairing score against sugar, tomato, 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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