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Onion Soup

A savory soup made with onions, butter, milk, water, bacon, sugar, salt, pepper, egg yolks, butter, and cream.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 11 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 ↓

Onion Soup

Ingredients

Directions

Make the soup base

  1. Fry the sliced onions in butter until light brown.

  2. Transfer the onions to a soup pot and add hot sweet milk, boiling water, bacon, sugar, salt, and white pepper.

  3. Simmer slowly for one hour and then strain through a sieve.

Finish and serve

  1. Stir in the beaten egg yolks, butter, and cream.

  2. Heat until just boiling and serve immediately.

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. Sugar + creamtop 9% of all pairs
    Smell alikemoderate
    Cooked together43,450 recipes

    Shared aroma: 2,3-butanedione (butter, sweet).

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

    Shared aroma: decanal (soap, orange peel).

  5. Butter + eggtop 17% of all pairs
    Smell alikemoderate
    Cooked together118,967 recipes

    Shared aroma: decanal (soap, orange peel).

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

What each ingredient does

Onions
Provide the main body and sweet, savory flavor of the soup as they cook down.
Egg yolks
Enrich the soup and thicken it slightly with a smooth, velvety texture.
Cream
Adds richness and a smooth, mellow texture to the finished soup.
Butter
Adds fat and flavor, and helps the onions brown during frying.
Milk
Adds body and a mild sweetness that softens the broth.

The step that matters

Heat until just boiling after adding the egg yolks. Egg yolks thicken by gentle heating and can curdle or turn grainy if overheated. Bringing the soup only to a boil, then serving at once, keeps the texture smooth.

Swap the white pepper

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

  1. Nutmegfits better
  2. Cinnamonfits better
  3. Garlicfits better
  4. White pepperthe original

Fit is the average pairing score against onion, butter, milk, sugar, 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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