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Onion-sauce

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

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. Peel the onions and quarter them.

  2. Place the onions in a saucepan, cover with water, and boil until the onions are tender.

  3. Strain the onions and chop them finely.

Make the sauce

  1. In a saucepan, combine the chopped onions and milk, and bring to a boil.

  2. In a bowl, mix the flour and butter into a paste.

  3. Stir the paste into the boiling milk and onions until it thickens.

  4. Season with pepper and salt to taste.

  5. Keep warm until ready to serve.

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. Flour + buttertop 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).

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

Onions
Provide the main flavour and body of the sauce once boiled and chopped.
Milk
Forms the liquid base of the sauce and gives it a smooth, creamy texture.
Flour
Thickens the milk as it heats, giving the sauce its body.
Butter
Adds fat and richness, and combines with the flour to form a paste that thickens smoothly.

The step that matters

Stirring the flour and butter paste into the boiling milk. Adding the paste to boiling liquid while stirring constantly lets the starch gelatinize and disperse evenly. Lumps form if the paste is added to cool liquid or not stirred, so the sauce may thicken unevenly.

Swap the onion

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

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

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