Skip to main content
Main

Onion Sauce

A creamy sauce made from boiled onions, butter, flour, and milk, seasoned with salt.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 ingredients
Jump to recipe ↓

Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓

Onion Sauce

Ingredients

Directions

Prepare the onions

  1. Peel the onions, place them in a saucepan, cover with water, and boil until tender, changing the water twice to reduce the strong flavor.

  2. Strain the water, chop the onions finely on a board.

Make the sauce

  1. Melt the butter in a saucepan, mix in the flour, and stir over heat for 1 minute.

  2. Gradually pour in the milk, stirring until it boils and thickens.

  3. Add the chopped onions and salt, and simmer for a few minutes.

  4. Serve hot.

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 + milktop 7% of all pairs
    Smell alikemoderate
    Cooked together81,283 recipes

    Shared aroma: (z)-4-heptenal (biscuit, cream).

  2. Butter + flourtop 12% of all pairs
    Smell alikelow
    Cooked together124,287 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 + buttertop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 recipes

    Shared aroma: decanal (soap, orange peel).

  5. Onion + flourtop 17% of all pairs
    Smell alikemoderate
    Cooked together32,460 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
Provide the main flavor and soft texture of the sauce once boiled and chopped.
Butter
Adds richness and fat that carries flavor and helps form the base roux.
Flour
Thickens the sauce with the butter as a roux when cooked with the milk.
Milk
Forms the liquid base of the sauce, which thickens as it heats and boils.

The step that matters

Gradually pour in the milk. Adding milk slowly while stirring keeps the flour and butter mixture smooth, so lumps do not form as the sauce thickens.

Swap the onion

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

  1. Potatofits better
  2. Arrowrootfits better
  3. Leekfits better
  4. Onionthe original

Fit is the average pairing score against butter, 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.

More onion sauce recipes

Brown 49White 27Sage 9Young 8Spanish 5Fried 3 See all 175 →

You might also like

Tomato SoupTomato Soup526 recipesBrown BreadBrown Bread461 recipesMutton BrothMutton Broth292 recipesYorkshire PuddingYorkshire Pudding264 recipes