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Onion Soup

A savory soup made with onions, butter, sugar, broth, bread, and Cognac brandy.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 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

  1. Melt the butter over medium heat in a stew-pan.

  2. Add the sliced onions and sugar, cooking until they turn golden brown.

  3. Pour in the broth and bring to a simmer.

  4. Add the bread and cook for a few more minutes.

  5. Stir in the Cognac brandy before serving.

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. Butter + cognac brandytop 13% of all pairs
    Smell alikemoderate
    Cooked together162 recipes

    Shared aroma: trans-2-nonenal (cardboard, fatty).

  3. Onion + buttertop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 recipes

    Shared aroma: decanal (soap, orange peel).

  4. Onion + breadtop 15% of all pairs
    Smell alikemoderate
    Cooked together8,676 recipes

    Shared aroma: 2,4-decadienal (seaweed).

  5. Butter + sugartop 17% of all pairs
    Smell alikemoderate
    Cooked together98,233 recipes

    Shared aroma: guaiacol (smoky, sweet).

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

What each ingredient does

Onions
Their sugars caramelise as they brown, giving the soup its sweet, deep flavour.
Butter
Fat carries flavour and helps the onions brown evenly in the pan.
Sugar
Speeds browning of the onions and adds a touch of sweetness.
Broth
Forms the liquid base of the soup and carries the flavours.
Bread
Thickens the soup slightly as it cooks and soaks up the broth.
Cognac brandy
Adds a strong aromatic note at the end of cooking.

The step that matters

Browning the onions. Onions must cook until deep golden brown, because the caramelisation of their sugars builds most of the soup's flavour. Pale onions leave the soup tasting flat.

Swap the onion

How well each one fits the dish's main ingredients (butter, sugar, bread, cognac brandy):

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

Fit is the average pairing score against butter, sugar, bread, cognac brandy. 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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