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Irish Walnut Ketchup

A fermented condiment made from walnut pulp, onions, anchovies, vinegar, and spices.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 10 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 ↓

Irish Walnut Ketchup

Ingredients

Directions

Prepare the walnut juice

  1. Extract the inner white part of green walnuts and pound them thoroughly.

  2. Strain off the juice to make it clear and let it stand for 12 hours.

  3. Strain the juice again.

Make the ketchup

  1. Add the onion, horse-radish, shallots, garlic, vinegar, and anchovies to each pint of juice. Mix well.

  2. Boil for 2 hours.

  3. When cold, strain the liquid until clear.

  4. Add the mixed spices, port, and soy sauce.

  5. Boil again for 45 minutes without straining the liquid. Keep the saucepan covered to retain the flavor.

Bottle

  1. Pour the ketchup into a jar and cover until cold.

  2. Transfer to clean, dry bottles and seal the corks.

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. Radish + shallottop 3% of all pairs
    Smell alikestrong
    Cooked together34 recipes

    Shared aroma: eucalyptol (eucalyptus, herbal).

  3. Horse + radishtop 4% of all pairs
    Smell alikemoderate
    Cooked together529 recipes

    Shared aroma: 2-methylbutyraldehyde (malty, chocolate).

  4. Shallot + garlictop 4% of all pairs
    Smell alikestrong
    Cooked together2,000 recipes

    Shared aroma: coumarin (sweet, hay).

  5. Shallot + clovetop 5% of all pairs
    Smell alikestrong
    Cooked together1,677 recipes

    Shared aroma: eucalyptol (eucalyptus, herbal).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Green walnuts
Provide the base juice that gives the ketchup its dark, savory body.
Anchovies
Add deep savory saltiness that rounds out the sauce.
Vinegar
Adds acidity that sharpens flavor and helps preserve the ketchup.
Port
Adds sweetness and fruity depth to the spiced sauce.
Soy sauce
Contributes salty, umami depth to the sauce.

The step that matters

Boil again for 45 minutes without straining, covered. Long simmering concentrates flavor and mellows the sharp raw notes of the horseradish, shallot and garlic. Keeping the pan covered limits evaporation and preserves the aromatic compounds in the spices, so the flavor stays rich rather than flat or overly reduced.

Swap the walnut

How well each one fits the dish's main ingredients (onion, horse, radish, shallot, clove, garlic, vinegar):

  1. Sesamefits better
  2. Beansfits better
  3. Chickpeafits better
  4. Walnutthe original

Fit is the average pairing score against onion, horse, radish, shallot, clove, garlic, 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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