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Onion Soup

A savory soup made from sliced onions, butter, water, milk, and seasonings.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 8 ingredients
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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 Soup

Ingredients

Directions

Prepare the onions

  1. Slice the onions and soak them in water or parboil and drain.

Make the soup

  1. Fry the onions in butter until yellow.

  2. Add 1 pint of water and cook until tender.

  3. Rub the mixture through a strainer.

  4. Stir in 1 pint of milk and heat.

  5. Add the butter and flour mixture, stirring well.

  6. Season with salt, pepper, and Bovril.

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

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

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

    Shared aroma: isobutyraldehyde (malty, green).

  4. Milk + flourtop 14% of all pairs
    Smell alikelow
    Cooked together78,219 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: decanal (soap, orange peel).

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 body and sweet, savoury flavour of the soup.
Butter
Fat for frying the onions, adding richness and helping them turn golden.
Milk
Adds creaminess and a mild sweetness to the soup.
Butter and flour mixture
Flour thickens the soup as it is stirred in, giving it body.

The step that matters

Stirring in the butter and flour mixture. Flour added to hot liquid can clump if not stirred well. Stirring thoroughly disperses the flour so it thickens the soup smoothly.

Swap the onion

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

  1. Potatofits better
  2. Capsicumfits better
  3. Chivefits better
  4. Onionthe original

Fit is the average pairing score against butter, milk, flour, pepper. 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 →

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