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Onion Soup

A creamy soup made from sliced onions, butter, flour, milk, potato, and sweet cream, seasoned with salt and pepper.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 8 ingredients
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Why it works: Onion and potato are a kitchen classic. They rank in the top 3% of all ingredient pairs, and cooks put them together in 9,023 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Onion Soup

Ingredients

Directions

  1. Slice the onions and brown them in butter with flour.

  2. Gradually stir in the scalding milk over a kettle of boiling water.

  3. Season with salt and pepper, then thicken with grated potato.

  4. Add sweet cream and serve very 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. Onion + potatotop 3% of all pairs
    Smell alikemoderate
    Cooked together9,023 recipes

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

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

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

  3. Butter + creamtop 8% of all pairs
    Smell alikemoderate
    Cooked together41,516 recipes

    Shared aroma: delta-dodecalactone (sweet, creamy).

  4. Pepper + potatotop 9% of all pairs
    Smell alikemoderate
    Cooked together8,305 recipes

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

  5. Milk + potatotop 9% of all pairs
    Smell alikemoderate
    Cooked together3,611 recipes

    Shared aroma: (e,z)-2,6-nonadienal (cucumber, melon).

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

What each ingredient does

Onions
Sweet, savory flavor base that softens and deepens as they brown in butter.
Butter
Fat that carries onion flavor and browns the onions for richness.
Flour
Thickens the browned onions and butter into a base that gives body to the soup.
Milk
Forms the main liquid of the soup, giving creamy body and mild sweetness.
Grated potato
Adds starch that further thickens the soup and gives it a smoother texture.
Sweet cream
Adds fat and richness, softening the finished soup's flavor and texture.

The step that matters

Stirring in the scalding milk gradually. Adding hot milk slowly while stirring and heating over boiling water keeps the flour mixture smooth and prevents lumps. Adding it all at once can cause the flour to clump instead of blending evenly into the liquid.

Swap the onion

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

  1. Chivefits about as well
  2. Leekfits about as well
  3. Spinachfits about as well
  4. Onionthe original

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