Name: Egg Sandwiches
Ingredients: buttered bread; chopped parsley; watercress; olives; hard-boiled eggs; mayonnaise; crisp lettuce leaves

Why it works: Watercress and lettuce match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 307 recipes. Both carry coumarin, which smells sweet, hay. The science ↓

Egg Sandwiches

Ingredients

Directions

Spread buttered bread with chopped parsley, watercress, or olives.
Cover with thin slices of hard-boiled egg.
Chop the eggs finely and mix with mayonnaise.
Lay the egg mixture between crisp lettuce leaves.
Alternatively, cover sliced boiled eggs with mayonnaise and place between lettuce leaves.

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.

Watercress + lettucetop 1% of all pairs

Smell alikestrong

Cooked together307 recipes

Shared aroma: coumarin (sweet, hay).
Parsley + watercresstop 2% of all pairs

Smell alikestrong

Cooked together469 recipes

Shared aroma: coumarin (sweet, hay).
Parsley + lettucetop 5% of all pairs

Smell alikestrong

Cooked together1,483 recipes

Shared aroma: trans-2-hexenal (green, leafy).
Olive + lettucetop 5% of all pairs

Smell alikestrong

Cooked together2,580 recipes

Shared aroma: trans-2-hexenal (green, leafy).
Parsley + olivetop 6% of all pairs

Smell alikestrong

Cooked together9,649 recipes

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

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

Swap the parsley

How well each one fits the dish's main ingredients (bread, watercress, olive, egg, lettuce):

Capersfits better
Tarragonfits about as well
Parsleythe original
Thymefits less well

Fit is the average pairing score against bread, watercress, olive, egg, lettuce. Candidates are from the same food group and used in at least 100 recipes.