Name: Pickled Onions
Ingredients: small onions; ½ cup milk; 1-2 gallons vinegar; 2 ½ teaspoons coarse sea salt; 2 ½ teaspoons allspice; 2 ½ teaspoons mace; 2 ½ teaspoons cloves; 2 ½ teaspoons mustard

Why it works: Allspice and clove match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 7,874 recipes. Both carry estragole, which smells anise, licorice. The science ↓

Pickled Onions

Ingredients

Directions

Peel the small onions as desired.
Boil the onions in milk and water for 5 minutes, then drain thoroughly.
In a large bowl, combine vinegar with salt, allspice, mace, cloves, and mustard.
Place the spices in bags and pour the boiling mixture over the 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.

Allspice + clovetop 1% of all pairs

Smell alikestrong

Cooked together7,874 recipes

Shared aroma: estragole (anise, licorice).
Allspice + mustardtop 2% of all pairs

Smell alikestrong

Cooked together1,928 recipes

Shared aroma: methyleugenol (clove, spice).
Onion + mustardtop 6% of all pairs

Smell alikestrong

Cooked together9,259 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Mace + clovetop 6% of all pairs

Smell alikelow

Cooked together8,400 recipes

Shared aroma: methyleugenol (clove, spice).
Allspice + macetop 7% of all pairs

Smell alikemoderate

Cooked together3,189 recipes

Shared aroma: methyleugenol (clove, spice).

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, milk, vinegar, allspice, clove, mustard):

Cinnamonfits better
Thymefits better
Tarragonfits better
Macethe original

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