Why it works: Potato and onion 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: egg, milk, wheat (auto-detected from the ingredients and method; we can miss things, so check labels)
Directions
The book gives no oven temperature. The 400°F (200°C) in the steps was added when the recipe was transcribed, as a starting point.
Prepare the potatoes
Prepare mashed potatoes as in 'Milk Potatoes,' omitting parsley.
Beat the egg with the lemon juice.
Remove the potatoes from heat, then carefully mix in the egg and lemon juice.
Reheat the mixture gently, avoiding boiling to prevent curdling.
Add the onion and shape
Fry the minced onion in butter until golden brown.
Combine the fried onion with the mashed potatoes and season with salt and pepper.
Form the mixture into cakes and dust with flour.
Bake
Place the cakes in a greased baking tin and dot with small pieces of butter.
Bake at 400°F (200°C) until golden brown.
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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Potato + oniontop 2% of all pairsAroma overlapstrongMentioned together9,019 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Pepper + lemontop 2% of all pairsAroma overlapstrongMentioned together27,039 recipes
Shared aroma: 2-nonenal (fatty, green).
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Potato + peppertop 5% of all pairsAroma overlapstrongMentioned together8,303 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Potato + buttertop 6% of all pairsAroma overlapstrongMentioned together6,445 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Butter + flourtop 6% of all pairsAroma overlaplowMentioned together122,858 recipes
Shared aroma: isobutyraldehyde (malty, green).
Butter and flour share little aroma chemistry, yet 122,858 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
What each ingredient does
- Potatoes
- Form the bulk of the cakes, providing a soft, starchy structure once mashed.
- Egg
- Binds the mashed potato so the cakes hold their shape and set when baked.
- Butter
- Adds richness and flavour, and helps the cakes brown in the oven.
- Onion
- Adds savoury sweetness and aroma when fried golden in butter.
- Lemon juice
- Adds a light acidity that brightens the flavour of the rich potato mixture.
The step that matters
Reheat the mixture gently, avoiding boiling. Egg proteins set and curdle when overheated, so boiling after the egg is added can make the potato grainy and split. Gentle heat keeps it smooth and binds it evenly.
Flavor stand-ins for the onion
How well each one fits the dish's main ingredients (potato, butter, pepper, egg, lemon, flour):
- Asparagusbetter flavor fit
- Capsicumbetter flavor fit
- Spinachbetter flavor fit
- Onionthe original
Fit is the average pairing score against potato, butter, pepper, egg, lemon, 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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