Why it works: Onion and vinegar are a kitchen classic. They rank in the top 14% of all ingredient pairs, and cooks put them together in 18,226 recipes. Both carry acetic acid, which smells sour, vinegar. The science ↓
Portugal Onions
Ingredients
Directions
Prepare
Chop the onion and baking apple into small pieces.
Mix the chopped onion and apple together in a bowl.
Pickle
Transfer the mixture to a pickle jar.
Pour enough boiling vinegar over the mixture to cover it and fill the jar.
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.
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Onion + vinegartop 14% of all pairsSmell alikemoderateCooked together18,226 recipes
Shared aroma: acetic acid (sour, vinegar).
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Apple + vinegartop 16% of all pairsSmell alikemoderateCooked together1,884 recipes
Shared aroma: isoamyl acetate (banana, fruity).
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Onion + appletop 19% of all pairsSmell alikemoderateCooked together3,206 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
- Onion
- Provides sharp, savoury flavour and crisp texture that softens slightly in the vinegar.
- Baking apple
- Adds tartness and firm bite that holds its shape during pickling.
- Boiling vinegar
- Acidifies the mixture, mellowing the onion's pungency and preserving the pieces.
The step that matters
Pouring the boiling vinegar. The vinegar must fully cover the chopped pieces so none are exposed to air, which can spoil them. Boiling vinegar helps draw out flavour and begins softening the onion and apple.
Swap the apple
How well each one fits the dish's main ingredients (onion, vinegar):
- Avocadofits better
- Plumfits better
- Cherryfits better
- Applethe original
Fit is the average pairing score against onion, vinegar. 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.
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