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Sauce

Onion Sauce

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

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 4 ingredients
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Why it works: Milk and butter 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 ↓

Onion Sauce

Ingredients

Directions

  1. Boil the milk and season to taste.

  2. Mix the flour with a little of the milk to form a paste.

  3. Add the butter and the flour mixture to the boiling milk.

  4. Once thickened, stir in the chopped onions that have been boiled.

  5. Cook for a few more minutes until heated through.

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

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

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

    Shared aroma: decanal (soap, orange peel).

  5. Flour + oniontop 17% of all pairs
    Smell alikemoderate
    Cooked together32,460 recipes

    Shared aroma: isobutyraldehyde (malty, green).

Flour and butter 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

Milk
Forms the liquid base that thickens into the sauce.
Flour
Thickens the milk into a smooth, coating sauce as it heats.
Butter
Adds fat and richness, giving the sauce a smoother mouthfeel.
Onions
Provide the main flavour and soft texture in the sauce.

The step that matters

Mixing the flour into a paste before adding it to the milk. Flour clumps if it is added dry or unevenly to hot liquid. Mixing it first with a little cold milk to a smooth paste lets the starch disperse evenly, so the sauce thickens without lumps.

Swap the onion

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

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

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