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Onion Soup

A creamy onion soup made with onions, water, salt, cream, egg yolks, butter, flour, pepper, and sugar.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 10 ingredients
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Why it works: Cream and butter are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 41,516 recipes. Both carry delta-dodecalactone, which smells sweet, creamy. The science ↓

Onion Soup

Ingredients

Directions

Prepare the onions

  1. Combine the chopped onions and 1 quart of cold water in a stew-pan.

  2. Bring the mixture to a boil.

  3. Drain the liquid.

  4. Return the onions to the pan.

  5. Pour 2 quarts of boiling water over the onions.

  6. Cook until the onions are very tender.

Finish the soup

  1. Add 1 tablespoon of salt.

  2. Stir in 1 cup of rich cream.

  3. Bring the soup to a boil.

  4. Remove the soup from heat.

  5. Mix in 2 egg yolks.

  6. Mix in a generous lump of butter that has been mixed with a little flour.

  7. Mix in a dash of pepper and a pinch of sugar.

  8. Let the soup bubble.

  9. Serve hot.

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. Cream + buttertop 8% of all pairs
    Smell alikemoderate
    Cooked together41,516 recipes

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

  2. Cream + sugartop 9% of all pairs
    Smell alikemoderate
    Cooked together43,450 recipes

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

  3. Onion + peppertop 11% of all pairs
    Smell alikemoderate
    Cooked together68,474 recipes

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

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

    Shared aroma: isobutyraldehyde (malty, green).

  5. Flour + sugartop 15% of all pairs
    Smell alikemoderate
    Cooked together92,116 recipes

    Shared aroma: phenylacetaldehyde (hawthorne, honey).

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
Cook down to tender pieces that give the soup its body and sweet flavour.
Rich cream
Adds richness and a smooth, mellow texture to the soup.
Egg yolks
Enrich and thicken the soup slightly when mixed in off the heat.
Butter
Adds fat and rich flavour, and with flour helps thicken the soup.

The step that matters

Mix in the egg yolks off the heat. Egg yolks thicken by gentle heat and can scramble or curdle if the soup is boiling. Removing the soup from heat before adding them keeps the texture smooth.

Swap the onion

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

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

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