Name: Pickled Onions
Ingredients: small white round onions (about the size of a marble); colorless vinegar; white pepper; ginger root; white mustard seed; mace; coarse sea salt

Why it works: Onion and mustard match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Pickled Onions

Ingredients

Directions

Peel the brown outer skin off the onions.
Simmer the onions in water until their outer layers are semi-transparent, then strain the water.
Allow the onions to dry.
Place the onions in an unglazed earthen jar.
Pour heated colorless vinegar over the onions until they are fully covered.
Add white pepper, ginger root, white mustard seed, mace, and coarse sea salt to taste.

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.

Onion + mustardtop 6% of all pairs

Smell alikestrong

Cooked together9,259 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Vinegar + mustardtop 7% of all pairs

Smell alikemoderate

Cooked together14,067 recipes

Shared aroma: isobutyraldehyde (malty, green).
Onion + gingertop 9% of all pairs

Smell alikemoderate

Cooked together7,595 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
White pepper + macetop 9% of all pairs

Smell alikemoderate

Cooked together1,695 recipes

Shared aroma: myrcene (balsamic, herbaceous).
Ginger + mustardtop 10% of all pairs

Smell alikemoderate

Cooked together2,456 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 white pepper

How well each one fits the dish's main ingredients (onion, vinegar, ginger, mustard, mace):

Allspicefits better
Clovefits better
Turmericfits better
White pepperthe original

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