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Sauce

Onion Sauce

A sauce made from boiled onions, milk, water, butter, pepper, and coarse sea salt.

From an old cookbook · modernised transcription
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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

  1. Peel the onions.

  2. Boil the onions in equal parts milk and water without adding salt.

  3. Once soft, drain the onions in a colander.

  4. Chop the onions finely and place them in a pan.

Finish

  1. Add butter, pepper, and coarse sea salt to taste.

  2. Use white onions for the best flavor.

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

    Shared aroma: decanal (soap, orange peel).

  4. Onion + milktop 20% of all pairs
    Smell alikemoderate
    Cooked together13,418 recipes

    Shared aroma: hexanal (green, grassy).

  5. Butter + peppertop 21% of all pairs
    Smell alikemoderate
    Cooked together85,593 recipes

    Shared aroma: trans-2-nonenal (cardboard, fatty).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Onions
Soften and release natural sweetness and savory aroma as they cook.
Milk
Adds creaminess and body, and its milk sugars brown lightly and add sweetness.
Butter
Adds fat for richness and a smooth, rounded mouthfeel.

The step that matters

Boiling the onions in milk and water. Milk contains proteins and sugars that can scorch and stick to the pan bottom at a hard boil. Keeping the heat moderate and stirring helps prevent burnt flavor and keeps the sauce smooth.

Swap the onion

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

  1. Potatofits better
  2. Capsicumfits better
  3. Tomatofits about as well
  4. Onionthe original

Fit is the average pairing score against milk, 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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