Why it works: Lentils and onion match in chemistry and in kitchens. They rank in the top 8% of all ingredient pairs, and cooks put them together in 1,221 recipes. Both carry coumarin, which smells sweet, hay. The science ↓
Lentil Soup
Ingredients
Directions
Soak and cook
Wash the lentils well and soak them in cold water overnight.
In the morning, place the lentils in a pan with the soaking water, adding enough to make 5 pints total.
Boil for 1 hour, then add the preserved vegetables and boil for another hour.
Finish
Rub the mixture through a colander, season to taste, and return to the pan to warm.
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.
-
Lentils + oniontop 8% of all pairsSmell alikestrongCooked together1,221 recipes
Shared aroma: coumarin (sweet, hay).
-
Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Lentils + peppertop 13% of all pairsSmell alikemoderateCooked together812 recipes
Shared aroma: coumarin (sweet, hay).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Lentils
- Break down during long cooking to give the soup its body and thick texture.
- Preserved vegetables
- Add concentrated savoury flavour as they cook into the broth over the second hour.
The step that matters
Boil the lentils fully before adding the preserved vegetables. Lentils must be fully softened after the first hour so they break down when rubbed through the colander. Under-cooked lentils stay gritty and make a coarse, uneven soup.
Swap the lentils
How well each one fits the dish's main ingredients (onion, pepper):
- Black-eyed peafits better
- Sesamefits better
- Beansfits better
- Lentilsthe original
Fit is the average pairing score against onion, 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 lentil soup recipes
You might also like
Tomato Soup526 recipes
Brown Bread461 recipes
Mutton Broth292 recipes
Yorkshire Pudding264 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.