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Boiled Onions

A simple boiled onion dish simmered in water, flavored with parsley, flour, and sweet milk.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 ingredients
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Why it works: Onion and parsley are a kitchen classic. They rank in the top 9% of all ingredient pairs, and cooks put them together in 25,843 recipes. Both carry 2,4-decadienal, which smells seaweed. The science ↓

Boiled Onions

Ingredients

Directions

Boil the onions

  1. Peel the onions and place them in a covered saucepan with cold water.

  2. Boil for one hour.

Finish and serve

  1. Add the chopped parsley and a little flour mixed with sweet milk.

  2. Boil for an additional five minutes, then 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. Onion + parsleytop 9% of all pairs
    Smell alikemoderate
    Cooked together25,843 recipes

    Shared aroma: 2,4-decadienal (seaweed).

  2. Parsley + flourtop 12% of all pairs
    Smell alikemoderate
    Cooked together16,675 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Flour + milktop 14% of all pairs
    Smell alikelow
    Cooked together78,219 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  4. Onion + flourtop 17% of all pairs
    Smell alikemoderate
    Cooked together32,460 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: hexanal (green, grassy).

Flour and milk barely smell alike, yet cooks put them together in 78,219 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
Become soft and mellow in flavor and sweetness as they boil for a long time.
Flour
Starch thickens the liquid as it heats, giving the milk a light, smooth body.
Sweet milk
Adds richness and creaminess to the liquid, softening the sauce's flavor.

The step that matters

Adding the flour mixed with milk. Flour clumps if poured in dry or unmixed. Stirring it into milk first lets it disperse evenly, so the starch can hydrate and thicken the liquid smoothly as it heats.

Swap the onion

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

  1. Arrowrootfits better
  2. Shallotfits better
  3. Parsnipfits better
  4. Onionthe original

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