Name: Pickled Onions
Ingredients: silver skinned onions; coarse sea salt; milk; water; tiny red peppers; 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 silver skinned onions and cover them with salt and water for 12 hours.
Drain the onions and cover them with equal parts of milk and water, then bring to a boil.
Pour off the liquid and place the onions in a colander, rinsing with cold water until clear.
Half fill jars with the onions, add two tiny red peppers, and continue filling the jars with onions.
Pour cold vinegar over the onions to completely fill the jars and seal while hot.

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).