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Onion Soup

A soup made from onions, milk, water, fowl or veal, bacon, pepper, salt, butter, flour, and toasted bread.

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

Onion Soup

Ingredients

Directions

Prepare

  1. Chop the onions.

  2. Boil the onions in equal parts milk and water.

Cook the soup

  1. Add the fowl or veal and bacon, seasoning with pepper and salt.

  2. Cook until the onions are soft and pulpy.

  3. Mix the butter and flour to thicken the soup.

  4. Remove the meat and serve the soup with small pieces of 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. Milk + buttertop 7% of all pairs
    Smell alikemoderate
    Cooked together81,283 recipes

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

  3. Milk + breadtop 11% of all pairs
    Smell alikemoderate
    Cooked together11,466 recipes

    Shared aroma: 2-undecenal (sweet).

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

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

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

    Shared aroma: isobutyraldehyde (malty, green).

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
Form the bulk of the soup, softening into a pulpy base that gives body and sweetness.
Butter and flour
Form a roux-style mixture that thickens the soup and gives it a smoother, richer texture.
Milk
Adds richness and creaminess to the broth, softening its flavor.
Bacon
Adds savory, smoky fat and flavor to the broth.

The step that matters

Cook until the onions are soft and pulpy. Onions must cook long enough to break down fully, because their starches and cell walls soften slowly. Undercooked onions leave the soup gritty and sharp instead of smooth and sweet.

Swap the onion

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

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

Fit is the average pairing score against milk, veal, pepper, butter, flour, 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 onion soup recipes

French 31Brown 15with Milk 7White 5Bavarian 4Bermuda 4 See all 236 →

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