Why it works: Potato and onion are a kitchen classic. They rank in the top 3% of all ingredient pairs, and cooks put them together in 9,023 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Cheap Soup
Ingredients
Directions
Prepare
Soak the split peas in cold water for a day.
Cook
In a boiler, combine soaked peas, water, boiled potatoes, herbs, salt, pepper, and sliced onions.
Cover tightly and boil gently for 5 hours, until only 2 gallons of soup remain.
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.
-
Potato + oniontop 3% of all pairsSmell alikemoderateCooked together9,023 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Peas + potatotop 9% of all pairsSmell alikemoderateCooked together1,016 recipes
Shared aroma: 2-isobutyl-3-methoxypyrazine (green bell pepper, earthy).
-
Potato + peppertop 9% of all pairsSmell alikemoderateCooked together8,305 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Pepper + oniontop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Peas + oniontop 13% of all pairsSmell alikemoderateCooked together5,460 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Split peas
- Break down during long cooking to give the soup its body and thickness.
- Boiled potatoes
- Their starch helps thicken the soup and make it feel creamy.
- Onions
- Add savory aroma and sweetness as they soften in the simmering soup.
The step that matters
Cover tightly and boil gently for 5 hours. A gentle simmer under a tight lid controls evaporation, so the peas break down and thicken evenly without scorching on the bottom of the pot.
Swap the peas
How well each one fits the dish's main ingredients (potato, pepper, onion):
- Beansfits better
- Black-eyed peafits better
- Sesamefits better
- Peasthe original
Fit is the average pairing score against potato, pepper, onion. 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
The 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.
Potato Croquettes255 recipes
Green Peas229 recipes
Potato Rolls78 recipes
Potato Chips53 recipes