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Sauce

White Onion Sauce

A sauce made from boiled onions, butter, milk, and flour.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 4 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 ↓

White Onion Sauce

Ingredients

Directions

Prepare the onions

  1. Peel the onions and boil them in hot water for 15 minutes.

  2. Transfer the onions to fresh hot water and boil gently until tender.

  3. Peel off the skins, cut out the roots, and squeeze the onions dry between two plates.

  4. Press the onions through a colander or chop them finely.

Make and serve the sauce

  1. In a saucepan, melt the butter with the milk and flour, stirring until it boils.

  2. Add the onions to the melted butter and stir until smooth and hot.

  3. Serve the sauce immediately in sauce tureens.

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

    Shared aroma: isobutyraldehyde (malty, green).

  3. Milk + flourtop 14% of all pairs
    Smell alikelow
    Cooked together78,219 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: decanal (soap, orange peel).

  5. Onion + flourtop 17% of all pairs
    Smell alikemoderate
    Cooked together32,460 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

Onions
Provide the main body and sweet flavour of the sauce once cooked and pressed smooth.
Butter
Adds richness and fat, carrying flavour and giving the sauce a smooth mouthfeel.
Milk
Adds liquid and creaminess, helping the butter and flour form a smooth base.
Flour
Thickens the butter and milk mixture so the sauce holds together.

The step that matters

Squeeze the onions dry. Excess water left in the onions would thin the sauce and dilute its flavour, so removing it before adding them to the butter keeps the texture thick and smooth.

Swap the onion

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

  1. Potatofits better
  2. Arrowrootfits better
  3. Leekfits better
  4. Onionthe original

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