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Sauce

Onion Sauce

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

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 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

Prepare the onions

  1. Boil the onions until tender, then mince them finely.

Make the sauce

  1. In a saucepan, bring the milk to a boil.

  2. Add the butter, salt, and pepper to the milk.

  3. Stir in the minced onions and the flour moistened with a little milk.

  4. Let the mixture cream over boiling water.

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. 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. Milk + flourtop 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 flavor and body of the sauce once boiled and minced.
Flour
Thickens the milk into a smooth sauce as it heats.
Milk
Forms the liquid base that the flour thickens into a creamy sauce.
Butter
Adds richness and a smooth, silky mouthfeel to the sauce.

The step that matters

Stirring in the flour. Flour added directly to hot milk can clump into lumps. Moistening it with a little cold milk first lets the starch disperse evenly, so the sauce thickens smoothly.

Swap the onion

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

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

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