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Spanish Onion Soup

A soup made with butter, shredded Spanish onion, flour, boiling water, salt, pepper, milk or cream, and bread pieces.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 8 ingredients
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Why it works: Wheat and milk are a kitchen classic. They rank in the top 6% of all ingredient pairs, and cooks put them together in 2,418 recipes. Both carry (e,z)-2,6-nonadienal, which smells cucumber, melon. The science ↓

Spanish Onion Soup

Ingredients

Directions

Make the soup

  1. Melt the butter in a stewpan over medium heat.

  2. Add the shredded onion and flour, stirring continually for 5 to 10 minutes.

  3. Pour in the boiling water, then season with salt and pepper.

  4. Skim the surface and boil until the onions are thoroughly cooked.

Serve

  1. In a tureen, place the pieces of bread and pour the soup over them.

  2. Add milk or cream to taste and serve.

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. Wheat + milktop 6% of all pairs
    Smell alikemoderate
    Cooked together2,418 recipes

    Shared aroma: (e,z)-2,6-nonadienal (cucumber, melon).

  2. Butter + breadtop 7% of all pairs
    Smell alikemoderate
    Cooked together27,232 recipes

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

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

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

  4. Wheat + breadtop 10% of all pairs
    Smell alikestrong
    Cooked together209 recipes

    Shared aroma: 2-acetyl-1-pyrroline (popcorn, roasted).

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

    Shared aroma: 2-undecenal (sweet).

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

What each ingredient does

Onion
Provides the main flavour and body as it cooks down into the soup.
Wheat flour or pea flour
Cooked with the butter and onion, it thickens the soup as it hydrates in the boiling water.
Butter or sweet dripping
Carries the onion as it softens and adds richness and fat to the soup.
Bread
Soaks up the hot soup, becoming soft and giving the dish its substance.

The step that matters

Stirring the onion and flour. Stirring continually over medium heat keeps the flour from scorching or sticking, since burnt flour gives a bitter taste and uneven thickening.

Swap the onion

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

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

Fit is the average pairing score against butter, wheat, pepper, milk, 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.

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