Name: Split Pea Soup
Ingredients: 1 cup split peas; 1 onion, sliced; 1 turnip, sliced; 1 carrot, sliced; 2 tablespoons oil for frying; 2 slices of bread, cut into small pieces and fried brown; small pieces of lemon

Why it works: Turnip and carrot match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 8,002 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Split Pea Soup

Ingredients

Directions

Prepare the peas

Soak the split peas overnight.
Boil the peas in water the next morning.

Fry the vegetables

Heat oil in a pan and fry the onion, turnip, and carrot until brown.

Finish and serve

Add the fried vegetables to the boiling peas and cook until ready to serve.
Strain the soup, then add the fried bread and small pieces of lemon.

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.

Turnip + carrottop 1% of all pairs

Smell alikestrong

Cooked together8,002 recipes

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

Smell alikestrong

Cooked together7,585 recipes

Shared aroma: coumarin (sweet, hay).
Onion + carrottop 6% of all pairs

Smell alikemoderate

Cooked together21,601 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Peas + carrottop 7% of all pairs

Smell alikemoderate

Cooked together2,994 recipes

Shared aroma: 2-isobutyl-3-methoxypyrazine (green bell pepper, earthy).
Peas + turniptop 8% of all pairs

Smell alikemoderate

Cooked together1,350 recipes

Shared aroma: coumarin (sweet, hay).

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

What each ingredient does

Split peas: Form the body of the soup as they soften and break down during long cooking.
Onion: Adds savoury depth and sweetness when fried until brown.
Turnip: Adds earthy flavour and body to the soup base.
Carrot: Adds sweetness and colour when fried until brown.
Bread: Fried until brown, it adds crunch and toasted flavour to the finished soup.

Swap the lemon

How well each one fits the dish's main ingredients (peas, onion, turnip, carrot, bread):

Pumpkinfits better
Avocadofits better
Limefits about as well
Lemonthe original

Fit is the average pairing score against peas, onion, turnip, carrot, bread. Candidates are from the same food group and used in at least 100 recipes.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.