Why it works: Cucumber and onion match in chemistry and in kitchens. They rank in the top 8% of all ingredient pairs, and cooks put them together in 6,050 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Cucumber Catsup
Ingredients
Directions
Prepare the pulp
Chop cucumbers and onions to a pulp.
Drain the mixture through a sieve overnight.
Season and bottle
Add salt, pepper, and vinegar to the pulp.
Seal the mixture in small bottles.
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 + oniontop 8% of all pairsSmell alikestrongCooked together6,050 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Cucumber + vinegartop 8% of all pairsSmell alikemoderateCooked together4,734 recipes
Shared aroma: 2-methylbutyl acetate (fruit).
-
Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Cucumber + peppertop 12% of all pairsSmell alikemoderateCooked together5,991 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Onion + vinegartop 14% of all pairsSmell alikemoderateCooked together18,226 recipes
Shared aroma: acetic acid (sour, vinegar).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Cucumbers
- Form the bulk of the ketchup, and their water content is drained off to thicken it.
- White onions
- Add savoury depth and a sharp aroma to the pulp.
- Vinegar
- Adds acidity that gives a sharp tang and helps keep the ketchup stable.
The step that matters
Drain the pulp overnight. Cucumbers are very watery. Draining removes excess liquid, so the ketchup thickens instead of tasting thin and diluted once bottled.
Swap the onion
How well each one fits the dish's main ingredients (cucumber, pepper, vinegar):
- Capsicumfits better
- Radishfits better
- Mustardfits better
- Onionthe original
Fit is the average pairing score against cucumber, pepper, 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.
You might also like
The free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.
Delicate Cake246 recipes
Boiled Frosting69 recipes
Citron Cake68 recipes
Scotch Cake63 recipes