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Lentil Soup

A hearty soup made with split lentils, onions, peppercorns, sugar, butter, and water.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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Why it works: Lentils and onion match in chemistry and in kitchens. They rank in the top 8% of all ingredient pairs, and cooks put them together in 1,221 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Lentil Soup

Ingredients

Directions

Prepare

  1. Wash the lentils well in two or three waters.

  2. Put the lentils into a saucepan with the onions, peppercorns, sugar, salt, and half the butter.

  3. Sweat the mixture for five minutes.

Cook and finish

  1. Pour in the boiling water and boil steadily for four hours.

  2. If the soup gets too thick, add a little more water or stock.

  3. Rub the soup through a sieve and return it to the saucepan.

  4. Stir in the remaining butter and season with salt and pepper to taste.

  5. Boil up and serve.

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. Lentils + oniontop 8% of all pairs
    Smell alikestrong
    Cooked together1,221 recipes

    Shared aroma: coumarin (sweet, hay).

  2. Butter + oniontop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 recipes

    Shared aroma: decanal (soap, orange peel).

  3. Butter + sugartop 17% of all pairs
    Smell alikemoderate
    Cooked together98,233 recipes

    Shared aroma: guaiacol (smoky, sweet).

  4. Lentils + buttertop 27% of all pairs
    Smell alikemoderate
    Cooked together486 recipes

    Shared aroma: isobutyraldehyde (malty, green).

  5. Lentils + sugartop 30% of all pairs
    Smell alikemoderate
    Cooked together119 recipes

    Shared aroma: 1-penten-3-one (fish, pungent).

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

What each ingredient does

Split lentils
Break down during long boiling to thicken the soup and give it body.
Butter
Adds richness and a smooth, rounded mouthfeel to the finished soup.
Onions
Sweat down to add savoury sweetness and aroma to the base.

The step that matters

Boil steadily for four hours. Lentils must soften fully and the soup must reduce to the right thickness. A gentle, steady boil keeps the liquid moving and cooks the lentils evenly, while a weak simmer or a hard boil can leave them grainy or scorch the bottom of the pan.

Swap the lentils

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

  1. Sesamefits better
  2. Almondfits better
  3. Chestnutfits better
  4. Lentilsthe original

Fit is the average pairing score against butter, onion, sugar. 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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