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Soup

Leek or Onion Soup

A creamy soup made with leeks or onions, broth, oatmeal or flour, egg yolks, and served with toasted bread.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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Why it works: Butter and bread are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 27,232 recipes. Both carry delta-decalactone, which smells sweet, creamy. The science ↓

Leek or Onion Soup

Ingredients

Directions

Make the soup

  1. Mix oatmeal with cold water until smooth.

  2. Gradually add broth until fully incorporated.

  3. Boil the mixture with chopped leeks or onions until creamy.

  4. Alternatively, use flour instead of oatmeal and stir vigorously for 5 minutes.

  5. Before serving, stir in beaten egg yolks mixed with a little broth.

Variation

  1. For a refreshing variation, fry chopped onions in oil or butter, pour boiling water over them, and serve with seasoned toasted bread.

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.

  1. Butter + breadtop 7% of all pairs
    Smell alikemoderate
    Cooked together27,232 recipes

    Shared aroma: delta-decalactone (sweet, creamy).

  2. Flour + leektop 8% of all pairs
    Smell alikestrong
    Cooked together328 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Flour + buttertop 12% of all pairs
    Smell alikelow
    Cooked together124,287 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  4. Mutton + breadtop 12% of all pairs
    Smell alikemoderate
    Cooked together1,488 recipes

    Shared aroma: delta-decalactone (sweet, creamy).

  5. Leek + peppertop 12% of all pairs
    Smell alikemoderate
    Cooked together965 recipes

    Shared aroma: coumarin (sweet, hay).

Flour and butter barely smell alike, yet cooks put them together in 124,287 recipes: they work on texture and structure more than aroma.

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

What each ingredient does

Oatmeal
Thickens the broth as it cooks, giving the soup a creamy body.
Broth
Forms the liquid base that carries the flavour of the soup.
Leeks or onions
Add sweetness and aroma as they soften in the boiling liquid.
Egg yolks
Enrich the soup and add richness and body when stirred in at the end.

The step that matters

Stirring in the egg yolks. Egg yolks can curdle or scramble if they meet very hot liquid directly. Mixing them with a little broth first and adding them off the heat helps keep the soup smooth.

Swap the leek

How well each one fits the dish's main ingredients (mutton, flour, egg, pepper, butter, bread):

  1. Shallotfits about as well
  2. Leekthe original
  3. Asparagusfits about as well
  4. Chivefits about as well

Fit is the average pairing score against mutton, flour, egg, pepper, butter, 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.

More leek soup recipes

Scotch 9Chicken 4Potato 4Welsh 3 See all 47 →

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