Name: Pickled Onions
Ingredients: small white onions; salt; water; milk; red pepper; cold vinegar

Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Pickled Onions

Ingredients

Directions

Peel the small white onions and soak them in a mixture of salt and water overnight.
Scald the onions in equal parts milk and water, bringing it just to a boil.
Drain the onions in a colander and rinse them with cold water.
Place the onions in bottles, adding one red pepper to each bottle.
Cover the onions with cold vinegar and seal the bottles.

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 + peppertop 11% of all pairs

Smell alikemoderate

Cooked together68,474 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + vinegartop 14% of all pairs

Smell alikemoderate

Cooked together18,226 recipes

Shared aroma: acetic acid (sour, vinegar).
Pepper + vinegartop 14% of all pairs

Smell alikemoderate

Cooked together27,814 recipes

Shared aroma: 4'-methylacetophenone (bitter almond).
Onion + milktop 20% of all pairs

Smell alikemoderate

Cooked together13,418 recipes

Shared aroma: hexanal (green, grassy).
Milk + peppertop 22% of all pairs

Smell alikemoderate

Cooked together26,984 recipes

Shared aroma: ethyl 2-methylbutyrate (fruity, apple).