Name: Tomato Soup
Ingredients: 1 slice onion; 2 tablespoons butter; 1 teaspoon salt; 2 tablespoons flour; ½ teaspoon baking soda; water

Why it works: Butter and flour are a kitchen classic. They rank in the top 12% of all ingredient pairs, and 124,287 recipes mention both. Both carry isobutyraldehyde, which smells malty, green. The science ↓

Tomato Soup

Ingredients

Directions

In a pot, sauté the onion in butter until soft.
Add salt and baking soda.
Mix the flour with an equal amount of water until smooth.
Gradually add more water until the mixture is thin enough to pour.
Stir the soup while adding the flour mixture, then boil for 5 minutes.
Strain the soup, add butter, and serve.

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.

Photo for illustrative purposes only · Contact us to use it

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much aroma chemistry they share, and how many recipes mention both.

Butter + flourtop 12% of all pairs

Aroma overlaplow

Mentioned together124,287 recipes

Shared aroma: isobutyraldehyde (malty, green).
Onion + buttertop 15% of all pairs

Aroma overlapmoderate

Mentioned together42,912 recipes

Shared aroma: decanal (soap, orange peel).
Onion + flourtop 17% of all pairs

Aroma overlapmoderate

Mentioned together32,460 recipes

Shared aroma: isobutyraldehyde (malty, green).

Butter and flour share little aroma chemistry, yet 124,287 recipes mention both: they likely work on texture and structure more than aroma.

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

Flavor stand-ins for the onion

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

Shallotbetter flavor fit
Leekbetter flavor fit
Arrowrootbetter flavor fit
Onionthe original

Fit is the average pairing score against butter, flour. Candidates are from the same food group and used in at least 100 recipes. This compares flavor only: it does not check the job the ingredient does in the dish (bulk, moisture, acidity, structure).