Why it works: Tomato and onion are a kitchen classic. They rank in the top 8% of all ingredient pairs, and 20,633 recipes mention both. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Tomato Sauce
Ingredients
Directions
Prepare
Strain the stewed tomatoes.
Chop the onions and fry them in the butter until tender.
Make the sauce
Add the salt and flour to the onions and cook until browned.
Slowly add the tomato juice until a gravy or sauce forms.
Serve over rice or other dishes.
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 + oniontop 8% of all pairsAroma overlapmoderateMentioned together20,633 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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Butter + oniontop 15% of all pairsAroma overlapmoderateMentioned together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Onion + flourtop 17% of all pairsAroma overlapmoderateMentioned together32,460 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Tomato + buttertop 22% of all pairsAroma overlapmoderateMentioned together6,918 recipes
Shared aroma: 3-hexenal (apple, fruity).
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
- Butter
- Fat that softens the onions and carries flavor into the sauce.
- Flour
- Thickens the liquid into a gravy-like sauce as it cooks with the onions.
- Onions
- Provide sweetness and savory depth as they soften and brown in the butter.
- Stewed tomatoes
- Provide the tomato juice and body that form the base of the sauce.
The step that matters
Cooking the flour with the onions until browned. Flour must cook in the fat long enough to lose its raw taste and to brown slightly, which builds flavor. Adding liquid too early can leave lumps, so the flour should be fully mixed in first.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (tomato, butter, flour):
- Okrabetter flavor fit
- Eggplantbetter flavor fit
- Potatobetter flavor fit
- Onionthe original
Fit is the average pairing score against tomato, butter, flour. 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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