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Onion Sandwich

A sandwich made with onions soaked in salt water, mixed with mayonnaise, and served between buttered bread.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 5 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 ↓

Onion Sandwich

Ingredients

Directions

Prepare the onion

  1. Cover the chopped onion with strong salt water.

  2. Let it sit for 3 hours.

  3. Drain the onion.

  4. Mix it with a good mayonnaise dressing.

Assemble

  1. Butter the slices of bread.

  2. Spread a generous amount of the onion mixture between them.

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. Onion + buttertop 15% of all pairs
    Smell alikemoderate
    Cooked together42,912 recipes

    Shared aroma: decanal (soap, orange peel).

  3. Onion + breadtop 15% of all pairs
    Smell alikemoderate
    Cooked together8,676 recipes

    Shared aroma: 2,4-decadienal (seaweed).

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

What each ingredient does

Onion
Salt water softens its sharp bite and mellows its flavour before it goes into the sandwich.
Mayonnaise dressing
Adds fat and moisture, binding the onion and keeping the filling creamy.
Bread
Provides the structure that holds the onion filling and carries it to the mouth.
Butter
Adds richness and fat to the bread, and creates a barrier that limits sogginess from the filling.

The step that matters

Draining the onion after soaking. If the onion is not drained well, excess water thins the mayonnaise and soaks into the bread, leaving the sandwich soggy and the filling loose.

Swap the onion

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

  1. Leekfits about as well
  2. Potatofits about as well
  3. Tomatofits about as well
  4. Onionthe original

Fit is the average pairing score against bread, butter. 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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