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 Sauce I
Ingredients
Directions
Make the tomato base
Cook the sliced onion with the tomatoes for 15 minutes.
Rub the mixture through a strainer.
Make the roux and sauce
In a separate pan, melt the butter and whisk in the flour to form a roux.
To retain the red color of the tomatoes, brown the butter and flour together before adding the tomatoes.
Add the strained tomato mixture to the roux and stir well.
If the tomatoes are very acidic, add a few grains of baking soda.
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 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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Butter + flourtop 12% of all pairsAroma overlaplowMentioned together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Onion + buttertop 15% of all pairsAroma overlapmoderateMentioned together42,912 recipes
Shared aroma: decanal (soap, orange peel).
Butter and flour share little aroma chemistry, yet 124,287 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
- Fresh stewed tomatoes
- Form the bulk of the sauce, supplying its liquid, flavour and red colour.
- Onion
- Adds savoury aroma and sweetness as it cooks down with the tomatoes.
- Butter
- Provides fat and flavour, and forms the base of the roux.
- Flour
- Thickens the sauce when cooked with butter to form a roux.
- Baking soda
- Neutralises some acidity in very acidic tomatoes.
The step that matters
Browning the butter and flour into a roux before adding the tomatoes. Cooking the flour fully in the butter removes its raw taste and helps prevent lumps when the liquid goes in. The recipe also ties this step to keeping the tomatoes' red colour, so the roux should be browned before the tomatoes are added.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (tomato, butter, flour, pepper):
- Capsicumbetter flavor fit
- Okrabetter flavor fit
- Eggplantbetter flavor fit
- Onionthe original
Fit is the average pairing score against tomato, butter, 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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