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Onion Soup

A creamy soup made from onions, butter, flour, milk, potato, and sweet cream.

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.

  4. Thicken the soup with grated potato.

  5. 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
Provide the main flavour and body of the soup when browned and softened.
Butter
Carries the browning of the onions and adds richness to the soup.
Flour
Browns with the butter and helps thicken the soup base.
Milk
Forms the liquid base of the soup and adds creaminess.
Grated potato
Adds starch that thickens the soup further.
Sweet cream
Adds fat and a smooth, rich finish at the end.

The step that matters

Stirring in the scalding milk gradually. Adding hot milk slowly over gentle heat while stirring keeps the flour smooth and prevents lumps, so the soup thickens evenly instead of curdling or clumping.

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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