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Sauce

Burnt Onion Sauce

A sauce made by cooking onions until almost black, then adding water, vinegar, soy sauce, and straining.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Cider and vinegar are a kitchen classic. They rank in the top 6% of all ingredient pairs, and cooks put them together in 3,431 recipes. Both carry 4-ethyl-2-methoxyphenol, which smells smoky, clove. The science ↓

Burnt Onion Sauce

Ingredients

Directions

Prepare the onions

  1. Peel the onions.

  2. Parboil the onions in salted water. Drain the onions and press them dry.

  3. Chop the onions to a pulp and place in a saucepan.

Make the sauce

  1. Add the granulated sugar. Cook slowly until the mixture is almost black.

  2. Moisten with equal parts cold water and strong cider vinegar. Once liquefied, strain through cheesecloth.

  3. Add the Japanese soy sauce.

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. Cider + vinegartop 6% of all pairs
    Smell alikemoderate
    Cooked together3,431 recipes

    Shared aroma: 4-ethyl-2-methoxyphenol (smoky, clove).

  2. Sugar + saucetop 13% of all pairs
    Smell alikestrong
    Cooked together5,147 recipes

    Shared aroma: ethanol (alcoholic, ethereal).

  3. Onion + vinegartop 14% of all pairs
    Smell alikemoderate
    Cooked together18,226 recipes

    Shared aroma: acetic acid (sour, vinegar).

  4. Sugar + vinegartop 15% of all pairs
    Smell alikemoderate
    Cooked together20,806 recipes

    Shared aroma: beta-damascenone (apple, rose).

  5. Onion + saucetop 19% of all pairs
    Smell alikelow
    Cooked together10,474 recipes

    Shared aroma: ethanol (alcoholic, ethereal).

Onion and sauce barely smell alike, yet cooks put them together in 10,474 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 bulk of the sauce and, once deeply browned, its dark, rich flavour.
Granulated sugar
Caramelises during slow cooking, adding sweetness and deeper browned flavour.
Strong cider vinegar
Adds acidity that balances the sweetness of the caramelised onions.
Japanese soy sauce
Adds savoury, salty depth and umami to the finished sauce.

The step that matters

Cook slowly until the mixture is almost black. Sugars and onion sugars caramelise and then burn quickly near the end. Cooking too fast or too hot can turn the sauce bitter rather than deeply browned, so low, patient heat and close attention matter.

Swap the onion

How well each one fits the dish's main ingredients (sugar, cider, vinegar, sauce):

  1. Mustardfits better
  2. Capsicumfits better
  3. Horseradishfits better
  4. Onionthe original

Fit is the average pairing score against sugar, cider, vinegar, sauce. 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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