Why it works: Onion and potato match in chemistry and in kitchens. They rank in the top 2% of all ingredient pairs, and 9,019 recipes mention both. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
The recipe
Ingredients
Contains: milk, wheat (auto-detected from the ingredients and method; we can miss things, so check labels)
Directions
Prepare the vegetables
Slice the vegetables, except for the peas, and fry them in dripping until brown.
Put the vegetables and herbs into a kettle and cover with cold water.
Cook slowly for 2 hours, reducing the liquid by one-third.
Finish the soup
Pulp the vegetables through a colander and return the soup to the fire.
Add the rice and peas, and stew for half an hour.
Season the soup, then stir in the butter and flour mixture with the sugar.
Simmer for 5 minutes and serve.
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 aroma chemistry they share, and how many recipes mention both.
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Onion + potatotop 2% of all pairsAroma overlapstrongMentioned together9,019 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Carrot + potatotop 3% of all pairsAroma overlapstrongMentioned together3,105 recipes
Shared aroma: 2-isobutyl-3-methoxypyrazine (green bell pepper, earthy).
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Potato + ricetop 3% of all pairsAroma overlapstrongMentioned together827 recipes
Shared aroma: 2-acetyl-1-pyrroline (popcorn, roasted).
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Carrot + peastop 4% of all pairsAroma overlapstrongMentioned together2,994 recipes
Shared aroma: 2-isobutyl-3-methoxypyrazine (green bell pepper, earthy).
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Potato + peastop 4% of all pairsAroma overlapstrongMentioned together1,016 recipes
Shared aroma: 2-isobutyl-3-methoxypyrazine (green bell pepper, earthy).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Butter and flour
- Thickens the soup into a smoother, richer body when stirred in at the end.
- Raw rice
- Swells as it cooks, adding body and thickening the soup.
- Potato
- Breaks down when pulped, giving the soup a thick, creamy texture.
- Onions
- Browning in dripping builds deep, savoury flavour in the base.
- White sugar
- Adds a little sweetness to balance the savoury vegetables and seasoning.
The step that matters
Frying the vegetables until brown. Browning caramelises the natural sugars and forms savoury flavour compounds. Pale vegetables give a flat, washed-out soup, so the colour should be deep before the water goes in.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (carrot, potato, peas, rice, sugar, butter, flour):
- Asparagusbetter flavor fit
- Leekbetter flavor fit
- Capsicumbetter flavor fit
- Onionthe original
Fit is the average pairing score against carrot, potato, peas, rice, sugar, 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).
“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.
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