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Onion Soup

A savory soup made from onions, butter, water, flour, milk, egg yolk, Parmesan, pimento, salt, and cayenne.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 10 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

Prepare the onions

  1. Chop the onions and cook them in 2 tablespoons of butter for 5 minutes.

  2. Add the cold water and cook for 30 minutes, then press through a sieve.

Make the sauce

  1. Melt the remaining butter in a pot, add the flour, scalded milk, and seasonings, and cook for 5 minutes.

  2. Combine the onion mixture with the milk mixture, then stir in the slightly beaten egg yolk, Parmesan cheese, and pimento.

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 + parmesan cheesetop 9% of all pairs
    Smell alikemoderate
    Cooked together4,163 recipes

    Shared aroma: guaiacol (smoky, sweet).

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

    Shared aroma: isobutyraldehyde (malty, green).

  4. Flour + milktop 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 once cooked and pressed through a sieve.
Flour
Thickens the milk and butter mixture into a smooth base for the soup.
Milk
Adds creaminess and body to the soup as the liquid in the sauce.
Egg yolk
Enriches the soup and adds richness and body when stirred in.
Parmesan cheese
Adds savory, salty flavor and a little richness to the finished soup.

The step that matters

Stirring in the egg yolk. Egg yolk can curdle or scramble if it meets very hot liquid directly. Beating it lightly and combining it gently into the warm soup helps it blend smoothly and thicken the soup without graininess.

Swap the onion

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

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

Fit is the average pairing score against butter, flour, milk, egg, parmesan cheese. 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 onion soup recipes

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