Why it works: Butter and flour are a kitchen classic. They rank in the top 12% of all ingredient pairs, and cooks put them together in 124,287 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓
Split Pea Soup
Ingredients
Directions
The book gives no cooking times; the times in the steps were added in transcription, so check for doneness rather than trusting the clock.
Prepare the peas
Wash the peas well and soak them in cold water for 24 hours (or overnight in lower altitudes).
Drain the peas and place them in a pot with fresh cold water.
Cook the soup
Bring to a boil, then reduce heat and simmer until peas are tender.
In a separate pan, melt the butter and stir in the flour to make a roux.
Add the roux to the soup, season with salt and pepper, and stir well.
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.
-
Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Peas + peppertop 15% of all pairsSmell alikemoderateCooked together5,331 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Peas + buttertop 16% of all pairsSmell alikemoderateCooked together4,887 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
-
Flour + peppertop 19% of all pairsSmell alikemoderateCooked together50,459 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Butter + peppertop 21% of all pairsSmell alikemoderateCooked together85,593 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
Butter and flour barely smell alike, yet cooks put them together in 124,287 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
- Dried split peas
- Form the main body of the soup and thicken it as they cook down.
- Butter
- Adds richness and carries flavour in the roux.
- Flour
- Thickens the soup when cooked with butter into a roux.
The step that matters
Make the roux and add it to the soup. Flour must be cooked in the butter before it goes into the liquid; stirring it in well prevents lumps and a raw floury taste, and the soup thickens as it heats.
Swap the peas
How well each one fits the dish's main ingredients (butter, flour, pepper):
- Almondfits better
- Black-eyed peafits better
- Chestnutfits better
- Peasthe original
Fit is the average pairing score against butter, flour, 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.
More split pea soup recipes
You might also like
Green Peas229 recipes
Green Peas Soup35 recipes
Tomato Soup526 recipes
Brown Bread461 recipesThe free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.