Name: Leek Soup
Ingredients: 2 medium onions; 6 average potatoes; 1 slice of bread; 4 leeks; butter; salt and pepper to taste

Why it works: Onion and potato are a kitchen classic. They rank in the top 3% of all ingredient pairs, and cooks put them together in 9,023 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Leek Soup

Ingredients

Directions

Prepare

Chop the leeks and onions into small pieces.

Cook the soup

Fry the leeks and onions in butter for 10 minutes.
Cut the potatoes in half and add them to the pot along with the slice of bread.
Cover the mixture with water and bring to a boil.

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.

Photo for illustrative purposes only · Contact us to use it

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 + potatotop 3% of all pairs

Smell alikemoderate

Cooked together9,023 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Onion + leektop 4% of all pairs

Smell alikestrong

Cooked together1,326 recipes

Shared aroma: ethyl butyrate (apple, fruity).
Potato + leektop 6% of all pairs

Smell alikemoderate

Cooked together30 recipes

Shared aroma: 1-octen-3-ol (mushroom, earthy).
Bread + buttertop 7% of all pairs

Smell alikemoderate

Cooked together27,232 recipes

Shared aroma: delta-decalactone (sweet, creamy).
Potato + peppertop 9% of all pairs

Smell alikemoderate

Cooked together8,305 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

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

What each ingredient does

Leeks: Their mild, sweet flavour forms the base of the soup as they soften.
Onions: Softened in butter, they add sweetness and depth to the soup base.
Potatoes: As they cook down, they thicken the soup and give it a creamy body.
Bread: As it breaks down in the liquid, it helps thicken the soup.
Butter: Frying the vegetables in butter carries flavour and adds richness.

Swap the leek

How well each one fits the dish's main ingredients (onion, potato, bread, butter, pepper):

Chivefits about as well
Capsicumfits about as well
Tomatofits about as well
Leekthe original

Fit is the average pairing score against onion, potato, bread, butter, pepper. 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.