Name: Onion Pickles
Ingredients: white onions, uniform size; coarse sea salt (for brine); vinegar (enough to cover onions); 2 ounces turmeric; celery seeds; white mustard seeds; horseradish; mixed spices

Why it works: Mustard and horseradish match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 1,832 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Onion Pickles

Ingredients

Directions

Remove the outer peel from the onions.
Make a brine with water and coarse sea salt; bring to a boil and pour over the onions.
Let the onions sit in the brine for 2-3 days.
Pour off the brine and make a new brine; let the onions sit for the same time.
Scald the vinegar with turmeric and pour it over the onions while very hot.
Let the onions stand for several days.
Pour off the vinegar and add hot vinegar seasoned with celery seeds, white mustard seeds, horseradish, and mixed spices.

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.

Mustard + horseradishtop 1% of all pairs

Smell alikestrong

Cooked together1,832 recipes

Shared aroma: coumarin (sweet, hay).
Celery + mustardtop 2% of all pairs

Smell alikemoderate

Cooked together4,169 recipes

Shared aroma: guaiacol (smoky, sweet).
Turmeric + mustardtop 3% of all pairs

Smell alikestrong

Cooked together2,279 recipes

Shared aroma: guaiacol (smoky, sweet).
Turmeric + horseradishtop 3% of all pairs

Smell alikestrong

Cooked together437 recipes

Shared aroma: coumarin (sweet, hay).
Turmeric + celerytop 4% of all pairs

Smell alikestrong

Cooked together1,356 recipes

Shared aroma: guaiacol (smoky, sweet).

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 (vinegar, turmeric, celery, mustard, horseradish):

Shallotfits better
Cauliflowerfits better
Radishfits better
Onionthe original

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