Name: Cucumber Catsup
Ingredients: 3 large cucumbers; 1 tablespoon salt; 1 teaspoon black pepper; a handful of grated horseradish; 1 large onion, grated; 1 pint strong vinegar

Why it works: Cucumber and horseradish match in chemistry and in kitchens. They rank in the top 2% of all ingredient pairs, and cooks put them together in 640 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Cucumber Catsup

Ingredients

Directions

Prepare

Peel and grate the cucumbers.
In a bowl, combine the grated cucumbers, salt, black pepper, horseradish, and grated onion.
Pour the strong vinegar over the mixture.

Bottle

Bottle the mixture and cork it loosely.

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.

Cucumber + horseradishtop 2% of all pairs

Smell alikestrong

Cooked together640 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Horseradish + oniontop 7% of all pairs

Smell alikestrong

Cooked together1,784 recipes

Shared aroma: coumarin (sweet, hay).
Cucumber + oniontop 8% of all pairs

Smell alikestrong

Cooked together6,050 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Cucumber + vinegartop 8% of all pairs

Smell alikemoderate

Cooked together4,734 recipes

Shared aroma: 2-methylbutyl acetate (fruit).
Pepper + horseradishtop 11% of all pairs

Smell alikemoderate

Cooked together2,646 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

Cucumbers: Provide the bulk of the ketchup and its fresh, watery base.
Salt: Draws moisture out of the cucumbers and seasons the mixture.
Onion: Adds savoury depth and aroma to the mixture.
Strong vinegar: Acidity that preserves the mixture and sharpens its flavour.

Swap the onion

How well each one fits the dish's main ingredients (cucumber, pepper, horseradish, vinegar):

Mustardfits better
Radishfits better
Cauliflowerfits better
Onionthe original

Fit is the average pairing score against cucumber, pepper, horseradish, 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.