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Soup

Orsaic of Onion Boup

A soup of sliced onions cooked in butter, thickened with flour and hot milk, then rubbed through a sieve.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 ingredients
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Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓

Orsaic of Onion Boup

Ingredients

Directions

Make the soup base

  1. In a large pan, heat the butter over medium heat.

  2. Add the sliced onions and cook slowly, shaking the pan occasionally, until the onions are very tender but not colored.

  3. Sprinkle the flour over the onions and stir until absorbed.

  4. Gradually add the hot milk, stirring continuously until the mixture thickens evenly.

  5. Once boiling, reduce heat, season with salt and pepper, and simmer for 10 minutes.

Finish and serve

  1. Rub the mixture through a sieve, pressing as much pulp through as possible.

  2. Return the soup to the heat until piping hot and serve immediately.

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

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

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

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

  3. Butter + flourtop 12% of all pairs
    Smell alikelow
    Cooked together124,287 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  4. Flour + milktop 14% of all pairs
    Smell alikelow
    Cooked together78,219 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: decanal (soap, orange peel).

Butter and flour barely smell alike, yet cooks put them together in 124,287 recipes: they work on texture and structure more than aroma.

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

What each ingredient does

White onions
Provide the main flavour and, once softened and pressed through a sieve, the body of the soup.
Butter
Carries the onions as they cook gently and adds richness to the finished soup.
Flour
Thickens the milk into a smooth, creamy base as it cooks with the butter and onions.
Milk
Forms the creamy liquid of the soup, thickened by the flour into a smooth texture.

The step that matters

Cooking the onions slowly without colouring them. Gentle heat softens the onions and draws out their sweetness without browning. Browning would add bitter, caramelised notes that change the soup's clean, creamy flavour.

Swap the onion

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

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

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