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Onion Soup

A savory soup made with onions, potatoes, celery, stock, milk, butter, flour, salt, and pepper.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Onion and potato are a kitchen classic. They rank in the top 3% of all ingredient pairs, and cooks put them together in 9,023 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Onion Soup

Ingredients

Directions

Prepare the vegetables

  1. Peel and slice the onions, potatoes, and celery.

Make the soup

  1. Heat the butter in a stewpan and cook the vegetables slowly for about 15 minutes, stirring frequently to prevent browning.

  2. Add the stock and simmer gently until the vegetables are tender, about 30 minutes.

  3. Rub the mixture through a fine sieve back into the stewpan.

  4. Stir in the milk and bring to a boil.

  5. Mix the flour smoothly with a little milk, pour it into the soup, stir, and simmer for a few minutes.

  6. Season 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. Onion + potatotop 3% of all pairs
    Smell alikemoderate
    Cooked together9,023 recipes

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

  2. Celery + peppertop 5% of all pairs
    Smell alikestrong
    Cooked together16,012 recipes

    Shared aroma: 4'-methylacetophenone (bitter almond).

  3. Potato + celerytop 7% of all pairs
    Smell alikemoderate
    Cooked together2,047 recipes

    Shared aroma: 4'-methylacetophenone (bitter almond).

  4. Milk + buttertop 7% of all pairs
    Smell alikemoderate
    Cooked together81,283 recipes

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

  5. Onion + celerytop 7% of all pairs
    Smell alikemoderate
    Cooked together18,518 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
Soften and build the sweet, savory base of the soup as they cook down.
Potatoes
Break down during simmering to give the soup body and a smooth, thick texture.
Butter
Carries the vegetables' flavour and adds richness while they cook gently.
Flour
Thickens the soup as it simmers, giving it a fuller, velvety body.
Milk
Adds creaminess and mellows the flavour of the finished soup.

The step that matters

Cook the vegetables slowly and stir often. Gentle heat softens the vegetables without browning them. Browning would add bitter, toasted notes that change the soup's clean, pale flavour and colour.

Swap the celery

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

  1. Parsleyfits better
  2. Thymefits better
  3. Garlicfits better
  4. Celerythe original

Fit is the average pairing score against milk, onion, potato, butter, flour, 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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