Name: Onions and Cucumbers
Ingredients: Cucumbers; Small onions; Vinegar; Water; Pepper; Coarse sea salt; Stock; Juice of 1 lemon; Sugar

Why it works: Pepper and lemon match in chemistry and in kitchens. They rank in the top 3% of all ingredient pairs, and cooks put them together in 27,047 recipes. Both carry trans-2-nonenal, which smells cardboard, fatty. The science ↓

Onions and Cucumbers

Ingredients

Directions

Peel the cucumbers and cut them into quarters.
Remove the seeds and cut each quarter into three pieces.
Peel the same number of small onions as cucumber pieces.
Soak cucumbers and onions in equal parts vinegar and water with some pepper and salt for 2 hours.
Drain the mixture and add enough stock to barely cover the vegetables.
Boil down until it reaches a glaze consistency.
Stir in the juice of a lemon and a little sugar.
Serve as a dish by itself or as an accompaniment to cutlets.

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.

Pepper + lemontop 3% of all pairs

Smell alikestrong

Cooked together27,047 recipes

Shared aroma: trans-2-nonenal (cardboard, fatty).
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).
Cucumber + lemontop 9% of all pairs

Smell alikestrong

Cooked together2,067 recipes

Shared aroma: trans-2-nonenal (cardboard, fatty).
Onion + peppertop 11% of all pairs

Smell alikemoderate

Cooked together68,474 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, vinegar, pepper, lemon, sugar):

Capsicumfits better
Radishfits better
Mustardfits better
Onionthe original

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