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Sauce Robert

A French onion sauce made with butter, onions, flour, stock, vinegar, mustard, and optional curry powder.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Onion and mustard match in chemistry and in kitchens. They rank in the top 6% of all ingredient pairs, and cooks put them together in 9,259 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Sauce Robert

Ingredients

Directions

Prepare

  1. Wash and slice the onions, removing the bitter parts.

Make the sauce

  1. In a stewpan, melt the butter and add the onions. Cover and cook, shaking occasionally, for about 15 minutes.

  2. Sprinkle flour over the onions and stir until browned.

  3. Once the onions are reduced to a pulp, moisten with hot stock.

  4. Season with salt, pepper, vinegar, and mustard. Add curry powder if desired.

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 + mustardtop 6% of all pairs
    Smell alikestrong
    Cooked together9,259 recipes

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

  2. Vinegar + mustardtop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  3. Pepper + mustardtop 9% of all pairs
    Smell alikemoderate
    Cooked together15,430 recipes

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

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

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

  5. Butter + flourtop 12% of all pairs
    Smell alikelow
    Cooked together124,287 recipes

    Shared aroma: isobutyraldehyde (malty, green).

Butter and flour 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
Break down into a pulp to form the body and sweet base of the sauce.
Butter
Cooks the onions gently and adds richness and flavor to the sauce.
Flour
Browns with the onions and thickens the sauce as it is moistened with stock.
French vinegar
Adds acidity that brightens the rich onion flavor.
French mustard
Adds sharp, pungent flavor that balances the sweetness of the onions.

The step that matters

Browning the flour with the onions. Flour stirred into the onions must brown without burning, since scorched flour gives a bitter taste. Cooking it briefly in the fat develops flavor and color before the stock thickens the sauce.

Swap the onion

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

  1. Shallotfits better
  2. Horseradishfits better
  3. Radishfits better
  4. Onionthe original

Fit is the average pairing score against butter, flour, pepper, vinegar, mustard. 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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