Name: Pickled Onions
Ingredients: small silver-skinned onions; brine (enough to float an egg); vinegar; a little mace; whole red pepper; a few bits of horseradish; cinnamon bark

Why it works: Horseradish and cinnamon match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 515 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Pickled Onions

Ingredients

Directions

Select small silver-skinned onions and remove all the outer skins with a knife.
Soak the cleaned onions in brine for three days.
Bring vinegar to a boiling point and add mace, whole red pepper, horseradish, and cinnamon bark.
Pour the hot vinegar mixture over the drained onions.

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 + cinnamontop 6% of all pairs

Smell alikestrong

Cooked together515 recipes

Shared aroma: coumarin (sweet, hay).
Onion + horseradishtop 7% of all pairs

Smell alikestrong

Cooked together1,784 recipes

Shared aroma: coumarin (sweet, hay).
Pepper + cinnamontop 9% of all pairs

Smell alikestrong

Cooked together4,890 recipes

Shared aroma: methyl cinnamate (strawberry).
Mace + cinnamontop 10% of all pairs

Smell alikemoderate

Cooked together3,611 recipes

Shared aroma: methyleugenol (clove, spice).
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

Swap the mace

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

Allspicefits better
Tarragonfits better
Dillfits better
Macethe original

Fit is the average pairing score against onion, egg, vinegar, pepper, horseradish, cinnamon. Candidates are from the same food group and used in at least 100 recipes.