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Lentil Soup

A simple lentil soup cooked with optional onion, seasoned with salt, and thickened with browned flour.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 6 ingredients
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Why it works: Lentils and flour match in chemistry and in kitchens. They rank in the top 5% of all ingredient pairs, and cooks put them together in 255 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓

Lentil Soup

Ingredients

Directions

Cook the lentils

  1. Cook the lentils in a small quantity of boiling water until half done.

  2. If desired, add the onion cut in halves or quarters.

  3. When the lentils are tender, remove the onion.

  4. Strain the lentils through a colander.

Finish the soup

  1. Add enough boiling water to make a total of 3 pints.

  2. Season with salt.

  3. Add cream or butter.

  4. Reheat to boiling.

  5. Thicken with the browned flour blended with a little cold water.

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 + flourtop 5% of all pairs
    Smell alikestrong
    Cooked together255 recipes

    Shared aroma: isobutyraldehyde (malty, green).

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

    Shared aroma: coumarin (sweet, hay).

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

    Shared aroma: isobutyraldehyde (malty, green).

  4. Onion + creamtop 18% of all pairs
    Smell alikelow
    Cooked together10,827 recipes

    Shared aroma: 2-nonanone (fruity, floral).

  5. Cream + flourtop 20% of all pairs
    Smell alikemoderate
    Cooked together30,481 recipes

    Shared aroma: acetaldehyde (pungent, ethereal).

Onion and cream barely smell alike, yet cooks put them together in 10,827 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

Lentils
Form the body of the soup and, as they soften, give it a thick, hearty texture.
Browned flour
Thickens the soup when blended with cold water and stirred into the hot liquid.
Cream or butter
Adds richness and a smoother, silkier mouthfeel to the finished soup.

The step that matters

Thicken with the browned flour blended with a little cold water.. Flour added directly to hot liquid clumps, because its starch granules swell unevenly. Blending it first with cold water separates the particles so the soup thickens smoothly.

Swap the onion

The recipe marks onion as optional. How well each one fits the dish's main ingredients (lentils, cream, flour):

  1. Arrowrootfits better
  2. Kalefits better
  3. Spinachfits better
  4. Onionthe original

Fit is the average pairing score against lentils, cream, flour. 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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