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Onion Soup

A simple soup made from sliced onions simmered in broth with butter, salt, and pepper, served over croutons.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Onion Soup

Ingredients

Directions

Prepare the onions

  1. Peel the onions.

  2. Slice the onions into small square pieces.

  3. Boil the onions in water for 5 minutes.

  4. Drain the onions.

Cook the soup

  1. Melt the butter in a stewpan.

  2. Add the onions, salt, and pepper.

  3. Cover the onions with broth.

  4. Let them simmer until well cooked.

Serve

  1. Serve the soup over croutons.

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

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

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

    Shared aroma: decanal (soap, orange peel).

  3. Butter + peppertop 21% of all pairs
    Smell alikemoderate
    Cooked together85,593 recipes

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

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 and sweet, savory flavor as they cook down in the broth.
Butter
Adds richness and fat, helping the onions soften and brown gently in the pot.
Broth
Supplies the liquid that simmers the onions and forms the base of the soup.

Swap the onion

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

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

Fit is the average pairing score against butter, pepper. 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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