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Onion Custard

A custard made with cooked onions, egg, milk, salt, and pepper, baked until set.

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 Custard

Ingredients

Directions

The book gives no oven temperature. The 350°F (175°C) in the steps was added when the recipe was transcribed, as a starting point.

Prepare

  1. Cook the onions until tender, then drain thoroughly.

  2. In a bowl, mix the egg, milk, salt, and pepper.

  3. Pour the custard mixture over the onions.

Bake and serve

  1. Bake gently at 350°F (175°C) until set.

  2. Serve as a vegetable dish.

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. Egg + milktop 18% of all pairs
    Smell alikemoderate
    Cooked together88,785 recipes

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

  3. Onion + milktop 20% of all pairs
    Smell alikemoderate
    Cooked together13,418 recipes

    Shared aroma: hexanal (green, grassy).

  4. Milk + peppertop 22% of all pairs
    Smell alikemoderate
    Cooked together26,984 recipes

    Shared aroma: ethyl 2-methylbutyrate (fruity, apple).

  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

Onions
Provide the main body and sweetness of the dish as they soften and caramelize slightly during cooking.
Egg
Sets the custard, binding the milk into a firm, sliceable texture when heated.
Milk
Adds moisture and richness, forming the liquid base that the egg sets into custard.

The step that matters

Bake gently until set. Egg proteins coagulate at moderate heat and can curdle or turn grainy and watery if overbaked or heated too fast. Gentle heat keeps the custard smooth and tender.

Swap the onion

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

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

Fit is the average pairing score against egg, milk, 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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