Name: To Pickle Onions
Ingredients: onions of uniform size; boiling brine; hot distilled vinegar; white wine vinegar (for white onions); best distilled vinegar (for brown onions); a little mace; ginger; whole pepper

Why it works: Ginger and pepper match in chemistry and in kitchens. They rank in the top 9% of all ingredient pairs, and cooks put them together in 6,800 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

To Pickle Onions

Ingredients

Directions

Soak onions in boiling brine.
When cold, drain the onions.
Place the onions in bottles.
Fill the bottles with hot distilled vinegar.
For white onions, use white wine vinegar; for brown onions, use the best distilled vinegar.
Add a little mace, ginger, and whole pepper to both types.

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.

Ginger + peppertop 9% of all pairs

Smell alikestrong

Cooked together6,800 recipes

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

Smell alikemoderate

Cooked together7,595 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + peppertop 11% of all pairs

Smell alikemoderate

Cooked together68,474 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Vinegar + white winetop 11% of all pairs

Smell alikemoderate

Cooked together1,776 recipes

Shared aroma: beta-damascenone (apple, rose).
Mace + gingertop 11% of all pairs

Smell alikelow

Cooked together2,152 recipes

Shared aroma: alpha-pinene (pine, turpentine).

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, vinegar, white wine, ginger, pepper):

Garlicfits better
Thymefits better
Clovefits better
Macethe original

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