Name: Egg and Sardine Sandwich
Ingredients: 6 hard cooked egg yolks; 1 can sardines, drained, skinned, and boned; ½ teaspoon coarse sea salt; ¼ teaspoon cayenne pepper; 2 teaspoons dry mustard; 1 tablespoon lemon juice or olive oil; round slices of bread; butter for spreading

Why it works: Pepper and lemon match in chemistry and in kitchens. They rank in the top 3% of all ingredient pairs, and cooks put them together in 27,047 recipes. Both carry trans-2-nonenal, which smells cardboard, fatty. The science ↓

Egg and Sardine Sandwich

Ingredients

6 hard cooked egg yolks
1 can sardines, drained, skinned, and boned
½ teaspoon coarse sea salt
¼ teaspoon cayenne pepper
2 teaspoons dry mustard
1 tablespoon lemon juice or olive oil
round slices of bread
butter for spreading

Directions

Make the filling

In a bowl, combine egg yolks and sardines.
Season with salt, cayenne pepper, and mustard.
Rub the mixture until smooth.
Add lemon juice or olive oil to create a paste.

Assemble

Spread the mixture between thin slices of buttered bread or on fresh wafers.

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.

Pepper + lemontop 3% of all pairs

Smell alikestrong

Cooked together27,047 recipes

Shared aroma: trans-2-nonenal (cardboard, fatty).
Bread + buttertop 7% of all pairs

Smell alikemoderate

Cooked together27,232 recipes

Shared aroma: delta-decalactone (sweet, creamy).
Pepper + mustardtop 9% of all pairs

Smell alikemoderate

Cooked together15,430 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Mustard + lemontop 11% of all pairs

Smell alikestrong

Cooked together3,816 recipes

Shared aroma: eucalyptol (eucalyptus, herbal).
Egg + breadtop 13% of all pairs

Smell alikemoderate

Cooked together22,662 recipes

Shared aroma: (e)-2-octenal (fatty, green).

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

What each ingredient does

Hard cooked egg yolks: Provide a rich, creamy base that binds the paste and adds body.
Sardines: Add savory, oily flavor and richness to the filling.
Dry mustard: Adds sharp, pungent flavor that cuts through the richness of the fish and yolks.
Lemon juice or olive oil: Adds acidity or fat that loosens the mixture into a smooth, spreadable paste.

The step that matters

Rub the mixture until smooth. Mashing the yolks and sardines thoroughly breaks down the fish and fat into a uniform emulsion-like paste. Lumps left behind give an uneven texture that spreads poorly and tastes unevenly seasoned.

Swap the mustard

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

Asparagusfits better
Capsicumfits better
Spinachfits better
Mustardthe original

Fit is the average pairing score against egg, pepper, lemon, 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.

Brown Bread461 recipes

Lemon Sauce236 recipes

White Bread80 recipes

Bread Omelette60 recipes

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Egg and Sardine Sandwich