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Onion Soup

A soup made with sautéed onions, water, butter, salt, pepper, served with toasted bread and grated cheese.

From an old cookbook · modernised transcription
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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

The book gives no cooking times; the times in the steps were added in transcription, so check for doneness rather than trusting the clock.

Make the soup

  1. Slice the onions and sauté them in butter until golden brown.

  2. Add water and bring to a boil.

  3. Season with coarse sea salt and pepper.

  4. Simmer for 30 minutes.

Serve

  1. Serve hot with toasted bread and grated cheese on top.

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. Bread + cheesetop 7% of all pairs
    Smell alikemoderate
    Cooked together2,130 recipes

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

  3. Butter + cheesetop 8% of all pairs
    Smell alikemoderate
    Cooked together7,962 recipes

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

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

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

  5. Onion + buttertop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 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 of the soup and, once browned, its deep sweet flavor.
Butter
Carries heat for browning the onions and adds richness and aroma.
Bread
Soaks up broth and adds texture when served toasted.
Grated cheese
Melts over the top, adding fat, saltiness and savory flavor.

The step that matters

Sauté the onions until golden brown. Slow browning through the Maillard reaction and caramelization builds the soup's deep, sweet flavor. Pale onions yield a flat, thin broth.

Swap the onion

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

  1. Capsicumfits better
  2. Tomatofits better
  3. Potatofits about as well
  4. Onionthe original

Fit is the average pairing score against butter, pepper, bread, 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.

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