Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and cooks put them together in 68,474 recipes. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Baked Onions
Ingredients
Directions
The book says “a slow oven”. The 300°F (150°C) in the steps is the modern equivalent, not the book's own figure.
Prepare the onions
Wash the onions without removing the skins.
Boil the onions in slightly salted water for 1 hour, changing the water twice with boiling hot water.
Remove the onions and place them on a cloth to absorb moisture.
Wrap each onion in buttered tissue paper, twisting the top to seal.
Bake and brown
Bake in a 300°F (150°C) oven for nearly 1 hour until tender.
Peel the onions and place them in a deep dish.
Brown the onions slightly by basting with butter for about 15 minutes.
Serve
Serve in a vegetable dish, pouring melted butter over them and sprinkling with pepper and salt.
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.
-
Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
-
Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
-
Butter + peppertop 21% of all pairsSmell alikemoderateCooked together85,593 recipes
Shared aroma: trans-2-nonenal (cardboard, fatty).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Onions
- Provide the main body of the dish, becoming soft and sweet as they cook slowly.
- Butter
- Adds moisture and richness, and helps the onion surface brown when basted.
- Coarse sea salt
- Seasons the onions and enhances their natural sweetness at the end.
The step that matters
Basting the onions with butter. Basting while the onions are in the dish helps their outer surfaces brown lightly and keeps them moist. Too little butter or heat can leave them pale and dry.
Swap the onion
How well each one fits the dish's main ingredients (butter, pepper):
- Capsicumfits better
- Potatofits better
- Carrotfits about as well
- Onionthe original
Fit is the average pairing score against butter, 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.
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