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Sauce

Tomato Catsup

A tomato-based condiment made by boiling tomatoes, onions, garlic, peppers, spices, and vinegar until thick.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 8 ingredients
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Why it works: Onion and garlic match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 29,058 recipes. Both carry furaneol, which smells caramel, strawberry. The science ↓

Tomato Catsup

Ingredients

Directions

Prepare

  1. Quarter the tomatoes and chop the onions and garlic.

  2. Combine all ingredients in a large pot.

Cook and finish

  1. Boil the mixture for a long time, stirring occasionally.

  2. Strain through a sieve.

  3. Add the vinegar last.

  4. Boil until thick enough.

Recipe from a historical cookbook (Internet Archive).

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.

  1. Onion + garlictop 1% of all pairs
    Smell alikestrong
    Cooked together29,058 recipes

    Shared aroma: furaneol (caramel, strawberry).

  2. Tomato + garlictop 3% of all pairs
    Smell alikemoderate
    Cooked together14,076 recipes

    Shared aroma: furaneol (caramel, strawberry).

  3. Allspice + peppertop 5% of all pairs
    Smell alikestrong
    Cooked together6,395 recipes

    Shared aroma: estragole (anise, licorice).

  4. Tomato + peppertop 7% of all pairs
    Smell alikemoderate
    Cooked together17,923 recipes

    Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

  5. Pepper + garlictop 8% of all pairs
    Smell alikemoderate
    Cooked together27,090 recipes

    Shared aroma: beta-phellandrene (minty, terpene).

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 provide its body, moisture and base flavor.
Vinegar
Adds sharp acidity that balances the sweetness and brightens the flavor.
Onions
Contribute savory sweetness and aromatic depth as they soften during cooking.
Garlic
Adds pungent aroma that mellows and deepens during long cooking.
Allspice
Provides warm, aromatic spice notes that season the sauce throughout.
Black pepper
Adds mild heat and sharp aroma to the sauce.

The step that matters

Boil until thick enough. Long boiling evaporates water and concentrates the tomato solids, which is what thickens ketchup. Stopping too early leaves it thin and watery, while boiling too long can scorch the sugars and darken the flavor. Adding the vinegar last keeps its sharpness from cooking away.

Swap the allspice

How well each one fits the dish's main ingredients (tomato, vinegar, pepper, onion, garlic):

  1. Cuminfits better
  2. Thymefits better
  3. Basilfits better
  4. Allspicethe original

Fit is the average pairing score against tomato, vinegar, pepper, onion, garlic. 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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