Name: Salad Sandwich
Ingredients: stale bread; butter; mustard flour; lettuce leaves; slices of underdone roast beef; slices of tomato; mayonnaise (optional)

Why it works: Mustard and lettuce match in chemistry and in kitchens. They rank in the top 1% of all ingredient pairs, and cooks put them together in 1,356 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓

Salad Sandwich

Ingredients

Directions

Cut neat slices of stale bread.
Butter the bread evenly with a mixture of butter and mustard flour.
Place a lettuce leaf on one slice of bread.
Add a slice of underdone roast beef and a slice of tomato.
Cover with another slice of buttered bread.
Press firmly together and cut into neat shapes.
For a chicken sandwich, substitute chicken for beef, omit mustard, and add a little mayonnaise on the lettuce.

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.

Mustard + lettucetop 1% of all pairs

Smell alikestrong

Cooked together1,356 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Lettuce + tomatotop 6% of all pairs

Smell alikemoderate

Cooked together1,655 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Bread + buttertop 7% of all pairs

Smell alikemoderate

Cooked together27,232 recipes

Shared aroma: delta-decalactone (sweet, creamy).
Beef + tomatotop 8% of all pairs

Smell alikemoderate

Cooked together5,448 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Bread + tomatotop 10% of all pairs

Smell alikemoderate

Cooked together1,013 recipes

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

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

Swap the tomato

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

Shallotfits better
Chivefits better
Leekfits better
Tomatothe original

Fit is the average pairing score against bread, butter, mustard, flour, lettuce, beef. Candidates are from the same food group and used in at least 100 recipes.