Name: CucuMBEK Catsup
Ingredients: 3 dozen cucumbers, peeled and finely chopped; 18 onions, peeled and finely chopped; ¾ pint table salt; 1 cup mustard seed; ½ cup ground black pepper; good cider vinegar

Why it works: Cucumber and mustard match in chemistry and in kitchens. They rank in the top 3% of all ingredient pairs, and cooks put them together in 2,281 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

CucuMBEK Catsup

Ingredients

3 dozen cucumbers, peeled and finely chopped
18 onions, peeled and finely chopped
¾ pint table salt
1 cup mustard seed
½ cup ground black pepper
good cider vinegar

Directions

Sprinkle cucumbers and onions with salt and let them drain in a sieve overnight.
Add mustard seed and black pepper, and mix well.
Cover the mixture with good cider vinegar.
Bottle the catsup and store in a cool, dry, dark place.

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 + mustardtop 3% of all pairs

Smell alikestrong

Cooked together2,281 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + mustardtop 6% of all pairs

Smell alikestrong

Cooked together9,259 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Cider + vinegartop 6% of all pairs

Smell alikemoderate

Cooked together3,431 recipes

Shared aroma: 4-ethyl-2-methoxyphenol (smoky, clove).
Mustard + vinegartop 7% of all pairs

Smell alikemoderate

Cooked together14,067 recipes

Shared aroma: isobutyraldehyde (malty, green).
Cucumber + oniontop 8% of all pairs

Smell alikestrong

Cooked together6,050 recipes

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

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

Swap the onion

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

Horseradishfits better
Radishfits better
Lettucefits better
Onionthe original

Fit is the average pairing score against cucumber, mustard, pepper, cider, vinegar. Candidates are from the same food group and used in at least 100 recipes.