Why it works: Onion and pepper are a kitchen classic. They rank in the top 11% of all ingredient pairs, and 68,474 recipes mention both. Both carry 2-isopropyl-3-methoxypyrazine, which smells earthy, pea. The science ↓
Onion Soup, Stanislaus Style
Ingredients
Directions
The book says “a moderate oven”. The 350°F (175°C) in the steps is the modern equivalent, not the book's own figure.
Prepare
Butter the crusts of the French rolls and place them in a 350°F (175°C) oven to crisp.
Cut off the ends of the onions, peel them, halve them, and slice them finely.
Make the soup
In a saucepan, melt the butter and fry the onions, stirring until nicely browned.
Add the hot water, season with salt and pepper, and include the bread crusts.
Cover the saucepan and bring to a boil, then transfer to the oven for 30 minutes before serving.
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 + peppertop 11% of all pairsAroma overlapmoderateMentioned together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Butter + oniontop 15% of all pairsAroma overlapmoderateMentioned together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Butter + peppertop 21% of all pairsAroma overlapmoderateMentioned 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
- White onions
- Browning in butter builds the sweet, deep flavour that forms the base of the soup.
- French rolls
- Crisped crusts add body and absorb liquid, giving the soup a thicker texture.
- Butter
- Fat for frying the onions, promoting browning and adding richness.
The step that matters
Browning the onions. Onions must be cooked until nicely browned, not just softened. Browning through the Maillard reaction and caramelisation creates the deep, sweet flavour the soup depends on, and pale onions yield a flat broth.
“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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