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Sauce

Brown Onion Sauce

A savory sauce made from browned onions, butter, gravy, port wine, and mushroom ketchup.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Butter and mushroom are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 12,525 recipes. Both carry trans-2-decenal, which smells waxy, orange. The science ↓

Brown Onion Sauce

Ingredients

Directions

Make the onion base

  1. Slice the large Spanish onions.

  2. In a frying pan, melt a bit of butter over low heat and add a few onion slices at a time, browning them.

  3. As the onions shrink and brown, add more slices until all are in the pan.

  4. Season with coarse sea salt, black pepper, and a dust of cayenne.

Finish the sauce

  1. Add ½ cup of rich brown gravy and a piece of butter rolled in flour.

  2. Let it simmer until the onions are tender and the mixture is smooth.

  3. Skim if necessary, then stir in ½ cup of port wine and ½ cup of mushroom ketchup.

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. Butter + mushroomtop 7% of all pairs
    Smell alikemoderate
    Cooked together12,525 recipes

    Shared aroma: trans-2-decenal (waxy, orange).

  2. Onion + mushroomtop 10% of all pairs
    Smell alikemoderate
    Cooked together10,626 recipes

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

  3. Port wine + mushroomtop 10% of all pairs
    Smell alikemoderate
    Cooked together570 recipes

    Shared aroma: guaiacol (smoky, sweet).

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

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

  5. Pepper + mushroomtop 11% of all pairs
    Smell alikemoderate
    Cooked together13,580 recipes

    Shared aroma: 2-nonenal (fatty, green).

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

What each ingredient does

Large spanish onions
Browned slowly in butter, they supply the sweet, deep flavour that forms the body of the sauce.
Butter
Carries the slow browning of the onions and adds richness to the sauce.
Rich brown gravy
Provides the liquid base and savoury depth that the onions simmer in.
Butter rolled in flour
Beurre manié: the flour thickens the sauce smoothly as the butter melts into it.
Port wine
Adds sweetness and a rich, fruity depth to the finished sauce.
Mushroom ketchup
Adds concentrated savoury, umami flavour that deepens the sauce.

The step that matters

Browning the onions slowly over low heat. Onions brown through gradual caramelisation of their sugars. If the heat is too high or the pan is crowded, they steam or scorch instead, leaving the sauce pale, bitter, or uneven.

Swap the onion

How well each one fits the dish's main ingredients (butter, pepper, flour, port wine, mushroom, ketchup):

  1. Shallotfits better
  2. Capsicumfits better
  3. Turnipfits better
  4. Onionthe original

Fit is the average pairing score against butter, pepper, flour, port wine, mushroom, ketchup. 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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