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Sauce

Onion Sauce

A creamy sauce made with onions, milk, cream, butter, and flour, seasoned with salt and pepper.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 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

The book gives no cooking times; the times in the steps were added in transcription, so check for doneness rather than trusting the clock.

Prepare the onions

  1. Peel and chop the onions.

  2. In a saucepan, melt the butter over medium heat.

  3. Add the chopped onions and sauté until soft.

Make the sauce

  1. Stir in the flour and cook for 1 minute.

  2. Gradually add the milk, stirring constantly until thickened.

  3. Stir in the cream and season with salt and pepper.

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. Cream + buttertop 8% of all pairs
    Smell alikemoderate
    Cooked together41,516 recipes

    Shared aroma: delta-dodecalactone (sweet, creamy).

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

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

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

    Shared aroma: isobutyraldehyde (malty, green).

  5. Milk + flourtop 14% of all pairs
    Smell alikelow
    Cooked together78,219 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
Softened in butter, they build the sweet, savoury base of the sauce.
Butter
Provides fat for cooking the onions and carries flavour through the sauce.
Flour
Thickens the sauce when cooked with butter and then combined with the milk.
Milk
Forms the liquid body of the sauce, which thickens as the flour starch swells.
Cream
Adds richness and a smoother, silkier texture to the finished sauce.

The step that matters

Gradually add the milk while stirring constantly. Adding the milk slowly while stirring keeps the flour evenly dispersed. Pouring it in all at once can form lumps that are hard to smooth out, and the sauce thickens as the starch swells with heat.

Swap the onion

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

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

Fit is the average pairing score against milk, cream, 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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