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Cream of Onion Soup

A creamy soup made from sautéed onions, water, milk, butter, flour, egg yolks, and cream.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓

Cream of Onion Soup

Ingredients

Directions

Make the soup

  1. Slice the onions and fry them in 1 tablespoon of butter over medium heat for 10 minutes without coloring.

  2. Add the boiling water and simmer for nearly an hour until the onions are soft.

  3. Strain the mixture and add the milk.

  4. Mix the flour and remaining butter into a paste, then stir it into the soup.

  5. Season to taste.

Finish and serve

  1. Just before serving, beat the egg yolks with the cream and quickly stir it into the soup off the heat to prevent curdling.

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 + milktop 7% of all pairs
    Smell alikemoderate
    Cooked together81,283 recipes

    Shared aroma: (z)-4-heptenal (biscuit, cream).

  2. Butter + creamtop 8% of all pairs
    Smell alikemoderate
    Cooked together41,516 recipes

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

  3. Butter + flourtop 12% of all pairs
    Smell alikelow
    Cooked together124,287 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  4. Milk + flourtop 14% of all pairs
    Smell alikelow
    Cooked together78,219 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  5. Onion + buttertop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 recipes

    Shared aroma: decanal (soap, orange peel).

Butter and flour 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

Onions
Provide the main flavor and body of the soup as they soften and sweeten slowly.
Butter
Adds richness and carries flavor while the onions cook gently without browning.
Flour
Thickens the soup, giving it a smooth, body-rich texture.
Egg yolks
Enrich and thicken the soup, adding silkiness and richness when gently heated.
Cream
Adds fat and richness, producing a smooth, velvety mouthfeel.

The step that matters

Adding the egg yolk and cream. Egg yolks thicken when heated, and if the soup is too hot they can scramble and curdle. Stirring them in quickly off the heat, after the soup has cooled slightly, keeps the texture smooth.

Swap the onion

How well each one fits the dish's main ingredients (butter, milk, flour, egg, cream):

  1. Potatofits better
  2. Leekfits better
  3. Chivefits better
  4. Onionthe original

Fit is the average pairing score against butter, milk, flour, egg, cream. 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.

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