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Portuguese Soup

A hearty soup of onions, tomatoes, and stale wholemeal bread, finished with grated cheese.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 9 ingredients
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Why it works: Bread and butter are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 27,232 recipes. Both carry delta-decalactone, which smells sweet, creamy. The science ↓

Portuguese Soup

Ingredients

Directions

Make the soup

  1. Slice the onions and fry them in butter until brown.

  2. Add the skinned and sliced tomatoes, water, herbs, pepper, and salt.

  3. Let the mixture boil gently for 1 hour.

Serve

  1. Cut the bread into dice and place it in a tureen.

  2. Pour the soup over the bread, cover, and let it stand for 10 minutes to soak.

  3. Sprinkle the grated cheese over the soup before serving.

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. Bread + buttertop 7% of all pairs
    Smell alikemoderate
    Cooked together27,232 recipes

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

  2. Cheese + breadtop 7% of all pairs
    Smell alikemoderate
    Cooked together2,130 recipes

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

  3. Tomato + peppertop 7% of all pairs
    Smell alikemoderate
    Cooked together17,923 recipes

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

  4. Onion + tomatotop 8% of all pairs
    Smell alikemoderate
    Cooked together20,633 recipes

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

  5. Cheese + buttertop 8% of all pairs
    Smell alikemoderate
    Cooked together7,962 recipes

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

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

What each ingredient does

Onions
Fried until brown in butter, they build the sweet, savoury base of the soup.
Tomatoes
Add moisture and acidity, breaking down during the long simmer into the body of the soup.
Stale wholemeal bread
Soaks up the hot soup, becoming soft and giving the dish its substance.
Grated cheese
Melts slightly into the hot soup, adding richness and savoury flavour.
Butter
Fat that carries the onions to a deep brown, adding richness and browned flavour.

The step that matters

Frying the onions until brown. Browning onions slowly in butter develops sweetness and depth through the Maillard reaction and caramelisation. Pale onions leave the soup flat-tasting, so they should be cooked until well coloured.

Swap the onion

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

  1. Capsicumfits better
  2. Potatofits better
  3. Asparagusfits about as well
  4. Onionthe original

Fit is the average pairing score against tomato, cheese, bread, butter, pepper. 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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