Name: Barley Soup
Ingredients: 1 lb barley; carrots; turnips; onions; parsley; olive oil or butter; sugar; vinegar; dry bread or crusts

Why it works: Carrot and parsley match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 8,053 recipes. Both carry 2,4-decadienal, which smells seaweed. The science ↓

Barley Soup

Ingredients

Directions

Soak the barley overnight in water.
Chop the carrots, turnips, onions, and parsley into small pieces.
In a pot, combine the soaked barley, chopped vegetables, and a little olive oil or butter.
Boil together for three hours, seasoning to taste.
For added flavor, include sugar, vinegar, and bits of dry bread or crusts.

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.

Carrot + parsleytop 1% of all pairs

Smell alikestrong

Cooked together8,053 recipes

Shared aroma: 2,4-decadienal (seaweed).
Carrot + turniptop 1% of all pairs

Smell alikestrong

Cooked together8,002 recipes

Shared aroma: coumarin (sweet, hay).
Barley + turniptop 2% of all pairs

Smell alikestrong

Cooked together629 recipes

Shared aroma: coumarin (sweet, hay).
Turnip + parsleytop 2% of all pairs

Smell alikestrong

Cooked together2,842 recipes

Shared aroma: coumarin (sweet, hay).
Turnip + oniontop 5% of all pairs

Smell alikestrong

Cooked together7,585 recipes

Shared aroma: coumarin (sweet, hay).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

Swap the onion

How well each one fits the dish's main ingredients (barley, carrot, turnip, parsley, olive, sugar, vinegar):

Parsnipfits better
Leekfits better
Beetrootfits better
Onionthe original

Fit is the average pairing score against barley, carrot, turnip, parsley, olive, sugar, vinegar. Candidates are from the same food group and used in at least 100 recipes.