Skip to main content
Main

Onion Soup

A savory soup made with thinly sliced onions, butter, flour, veal broth, and salt.

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

Why it works: Butter and flour are a kitchen classic. They rank in the top 12% of all ingredient pairs, and cooks put them together in 124,287 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓

Onion Soup

Ingredients

Directions

Prepare and cook the onions

  1. Slice the onions very thinly.

  2. Melt the butter in a pot, then add the onions and flour and cook until tender.

Simmer and finish

  1. Pour in the veal broth and bring to a boil for 20 minutes.

  2. Skim the surface, season with salt, and add a liaison.

  3. Whisk to combine, then let it simmer before serving.

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

    Shared aroma: isobutyraldehyde (malty, green).

  2. Onion + buttertop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 recipes

    Shared aroma: decanal (soap, orange peel).

  3. Onion + vealtop 17% of all pairs
    Smell alikelow
    Cooked together6,841 recipes

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

  4. Onion + flourtop 17% of all pairs
    Smell alikemoderate
    Cooked together32,460 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  5. Butter + vealtop 23% of all pairs
    Smell alikemoderate
    Cooked together9,381 recipes

    Shared aroma: 3-hexenal (apple, fruity).

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
Form the soup's main body and, when cooked slowly in butter, add natural sweetness.
Butter
Carries the onions' flavor and adds richness, helping them soften and brown gently.
Flour
Thickens the broth and gives the soup a smoother, more body-rich texture.
Veal broth
Serves as the liquid base, supplying the soup's savory, meaty flavor.

The step that matters

Cooking the onions with the flour until tender. Cooking the flour with the butter and onions removes its raw taste and lets it thicken the broth evenly. Cooking too quickly can scorch the butter and brown the onions unevenly.

Swap the onion

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

  1. Shallotfits better
  2. Leekfits better
  3. Chivefits better
  4. Onionthe original

Fit is the average pairing score against butter, flour, veal. 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 soup recipes

French 31Brown 15with Milk 7White 5Bavarian 4Bermuda 4 See all 236 →

You might also like

Veal PattiesVeal Patties50 recipesBeef, Mutton, or Veal BrothBeef, Mutton, or Veal Broth6 recipesTomato SoupTomato Soup526 recipesBrown BreadBrown Bread461 recipes