Name: Pickled Onions
Ingredients: small round onions; coarse sea salt; water; milk; white vinegar; white peppercorns

Why it works: Onion and vinegar are a kitchen classic. They rank in the top 14% of all ingredient pairs, and cooks put them together in 18,226 recipes. Both carry acetic acid, which smells sour, vinegar. The science ↓

Pickled Onions

Ingredients

Directions

Peel the outer skin off the onions.
Soak the onions in a strong saltwater solution for 3 to 4 days, changing the water several times.
Drain and wipe the onions dry.
Place the onions in boiling milk and let it cool.
Drain and dry each onion with a cloth.
Bottle the onions and pour over them white vinegar boiled with white peppercorns.
Cork the bottle well.

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 + vinegartop 14% of all pairs

Smell alikemoderate

Cooked together18,226 recipes

Shared aroma: acetic acid (sour, vinegar).
Onion + milktop 20% of all pairs

Smell alikemoderate

Cooked together13,418 recipes

Shared aroma: hexanal (green, grassy).
Milk + vinegartop 28% of all pairs

Smell alikemoderate

Cooked together2,949 recipes

Shared aroma: isoamyl acetate (banana, pear).