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Onion Tortilla

A fried egg and onion mixture cooked in butter, seasoned with salt and pepper.

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

Ingredients

Directions

Prepare

  1. Beat the eggs well and season with salt and pepper.

  2. Melt the butter in a sauté pan until very hot.

  3. Slice the onions and fry them in the butter.

Cook the omelette

  1. Pour the eggs into the pan, shake it well, and run a knife around the sides to prevent sticking.

  2. Brown lightly on one side.

  3. Turn the tortilla with a plate and brown the other side.

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

    Shared aroma: decanal (soap, orange peel).

  3. Egg + buttertop 17% of all pairs
    Smell alikemoderate
    Cooked together118,967 recipes

    Shared aroma: decanal (soap, orange peel).

  4. Butter + peppertop 21% of all pairs
    Smell alikemoderate
    Cooked together85,593 recipes

    Shared aroma: trans-2-nonenal (cardboard, fatty).

  5. Egg + peppertop 33% of all pairs
    Smell alikelow
    Cooked together50,580 recipes

    Shared aroma: 2-nonenal (fatty, green).

Egg and pepper barely smell alike, yet cooks put them together in 50,580 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

Eggs
Set into the structure of the omelette as they cook, holding the onions together.
Spanish onion
Softens and sweetens as it fries in butter, adding flavour and moisture to the eggs.
Butter
Fats the pan so the eggs and onions don't stick and gives a rich, browned flavour.

The step that matters

Pour the eggs into the pan, shake it well, and run a knife around the sides to prevent sticking.. Eggs set quickly on hot fat. Shaking keeps the mixture moving so it cooks evenly, and loosening the edges lets the omelette release without tearing or sticking to the pan.

Swap the onion

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

  1. Capsicumfits better
  2. Asparagusfits better
  3. Chivefits better
  4. Onionthe original

Fit is the average pairing score against egg, 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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