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Sauce Robert

A brown butter and onion sauce with flour, gravy, mustard, vinegar, and lemon juice.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Pepper and lemon match in chemistry and in kitchens. They rank in the top 3% of all ingredient pairs, and cooks put them together in 27,047 recipes. Both carry trans-2-nonenal, which smells cardboard, fatty. The science ↓

Sauce Robert

Ingredients

Directions

  1. Melt the butter in a saucepan over medium heat until it begins to brown.

  2. Add the diced onions and fry until they are brown but not burnt.

  3. Stir in the flour and fry for another minute.

  4. Add the gravy, pepper, and salt, and simmer gently for 10 minutes, skimming as needed.

  5. Before serving, stir in the mustard, vinegar, and lemon juice, and do not let it boil after adding the mustard.

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. Pepper + lemontop 3% of all pairs
    Smell alikestrong
    Cooked together27,047 recipes

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

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

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

  3. Mustard + vinegartop 7% of all pairs
    Smell alikemoderate
    Cooked together14,067 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

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

  5. Mustard + lemontop 11% of all pairs
    Smell alikestrong
    Cooked together3,816 recipes

    Shared aroma: eucalyptol (eucalyptus, herbal).

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

What each ingredient does

Butter
Provides fat and richness, and its browning adds a nutty flavour to the base.
Onions
Browning them adds sweetness and savoury depth to the sauce.
Flour
Frying it with the butter forms a roux that thickens the sauce.
Gravy
Supplies the liquid and savoury body that the sauce is built on.
Prepared mustard
Adds sharp flavour and a little emulsifying body when stirred in at the end.
Vinegar
Adds acidity that brightens the rich, savoury sauce.

The step that matters

Adding the mustard, vinegar, and lemon juice off the boil. Boiling after the mustard is added can make the sauce taste harsh and may cause it to separate. Keeping it just below a boil preserves a smooth texture and a bright, balanced flavour.

Swap the lemon

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

  1. Avocadofits better
  2. Limefits better
  3. Lemonthe original
  4. Mangofits about as well

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