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Soup

Onion Soup

A soup made from sliced onions, fat, flour, water or stock, seasoned with salt and pepper, topped with grated cheese.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Onion Soup

Ingredients

Directions

Prepare the onions

  1. Skin and scald the onions, then dry and slice them thinly.

  2. Fry the onions in hot fat until pale yellow.

Make the soup

  1. Stir in the flour, then add the cold water or stock.

  2. Bring to a boil, then add salt and pepper.

  3. Simmer for 20 minutes, stirring constantly.

  4. Optionally, pass through a sieve.

Serve

  1. Pour into a tureen over the grated cheese.

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

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

  2. Onion + cheesetop 16% of all pairs
    Smell alikemoderate
    Cooked together4,849 recipes

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

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

    Shared aroma: isobutyraldehyde (malty, green).

  4. Pepper + cheesetop 18% of all pairs
    Smell alikemoderate
    Cooked together7,861 recipes

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

  5. Flour + peppertop 19% of all pairs
    Smell alikemoderate
    Cooked together50,459 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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 as they soften and sweeten.
Flour
Thickens the soup as it cooks with the liquid, giving it body.
Grated cheese
Melts into the hot soup, adding richness and savoury flavour.

The step that matters

Frying the onions until pale yellow. Frying gently until pale yellow builds sweetness without browning. Deep browning would turn the soup bitter, while under-cooked onions taste harsh and raw.

Swap the onion

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

  1. Capsicumfits better
  2. Mustardfits better
  3. Spinachfits better
  4. Onionthe original

Fit is the average pairing score against flour, pepper, cheese. 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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