Name: Lemon Pickle or Catsup
Ingredients: 6 small lemons; 3 ounces coarse sea salt; 2 ½ ounces finely scraped horseradish; 2 ounces shallots or 1 ½ ounces garlic; 1 ½ pints boiling vinegar; ½ ounce bruised ginger; ¼ ounce whole white pepper; 2 blades of mace

Why it works: Horseradish and shallot match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 376 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Lemon Pickle or Catsup

Ingredients

Directions

Prepare the lemons

Divide the lemons into quarters and remove all visible seeds.
Sprinkle the salt over the lemons and let them sit for a week, turning occasionally.
After a week, place the lemons in a stone jar with their liquid.

Make the pickle

Add horseradish, shallots (or garlic), and pour in the boiling vinegar.
Simmer ginger, white pepper, and mace in the vinegar for 2-3 minutes before adding to the jar.

Mature

Let the pickle sit in a warm place for 2-3 months before using, but it can be strained after 4-5 months.

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.

Horseradish + shallottop 1% of all pairs

Smell alikestrong

Cooked together376 recipes

Shared aroma: coumarin (sweet, hay).
Lemon + gingertop 5% of all pairs

Smell alikestrong

Cooked together5,154 recipes

Shared aroma: beta-phellandrene (minty, terpene).
Lemon + shallottop 6% of all pairs

Smell alikestrong

Cooked together2,523 recipes

Shared aroma: eucalyptol (eucalyptus, herbal).
Shallot + gingertop 7% of all pairs

Smell alikemoderate

Cooked together565 recipes

Shared aroma: eucalyptol (eucalyptus, herbal).
Lemon + horseradishtop 9% of all pairs

Smell alikestrong

Cooked together1,155 recipes

Shared aroma: coumarin (sweet, hay).

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

What each ingredient does

Lemons: Provide the main body and sharp citrus flavour that the pickle is built around.
Coarse sea salt: Draws liquid out of the lemons and helps preserve them during the long salting.
Horseradish: Adds pungent heat that mellows and deepens as the pickle matures.
Vinegar: Acidity that preserves the pickle and sharpens the overall flavour.
Shallots or garlic: Adds savoury aromatic depth to the pickle.

The step that matters

Salting the lemons for a week. The salt must draw out enough liquid and penetrate the fruit over the full week. Turning the lemons helps the salt reach all surfaces evenly, so the lemons soften and cure consistently before the vinegar is added.

Swap the white pepper

How well each one fits the dish's main ingredients (lemon, horseradish, shallot, vinegar, ginger, mace):

Tarragonfits better
Allspicefits better
Turmericfits better
White pepperthe original

Fit is the average pairing score against lemon, horseradish, shallot, vinegar, ginger, mace. 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.

Lemon Sauce236 recipes

Horseradish Sauce17 recipes

Tomato Soup526 recipes

Brown Bread461 recipes

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Lemon Pickle or Catsup