📝 About This Recipe
A cornerstone of Scandinavian street food and home cooking, Rostad Lök is the crunch that defines the classic Swedish hot dog and Danish Smørrebrød. These golden-brown ribbons are meticulously fried to achieve a shattering crispness balanced by the deep, concentrated sweetness of caramelized yellow onions. Far superior to store-bought versions, this homemade rendition brings a professional chef’s touch to your pantry staples.
🥗 Ingredients
The Onions
- 4 large Yellow Onions (firm and heavy for their size)
- 1/2 cup Whole Milk (for soaking to remove bitterness)
The Coating
- 1/2 cup All-purpose Flour (sifted)
- 2 tablespoons Cornstarch (for extra crunch)
- 1.5 teaspoons Fine Sea Salt (plus extra for finishing)
- 1/2 teaspoon Granulated Garlic (for subtle savory depth)
- 1/4 teaspoon Sweet Paprika (for a golden hue)
- 1/4 teaspoon White Pepper (finely ground)
Frying Medium
- 3 cups Neutral Vegetable Oil (such as rapeseed or sunflower oil)
👨🍳 Instructions
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1
Peel the onions and slice them in half from pole to pole. Slice them into very thin, uniform semi-circles (about 2-3mm thick) using a mandoline or a very sharp chef's knife.
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2
Place the sliced onions in a large bowl and pour the milk over them. Toss gently to coat and let them soak for 10 minutes; this helps the flour stick and tempers the raw onion bite.
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3
While the onions soak, whisk together the flour, cornstarch, 1.5 teaspoons of salt, garlic powder, paprika, and white pepper in a large, shallow dish or a gallon-sized freezer bag.
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4
Drain the onions thoroughly in a colander. Pat them very dry with paper towels—excess moisture is the enemy of crispiness.
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5
Working in batches, toss a handful of onions into the flour mixture. Shake well to ensure every strand is separated and fully coated.
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6
Transfer the coated onions to a fine-mesh sieve and shake vigorously to remove all excess flour. You want a thin, translucent coating, not a thick batter.
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7
Heat the vegetable oil in a heavy-bottomed pot or Dutch oven to 160°C (320°F). Use a candy or deep-fry thermometer to maintain this specific temperature.
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8
Carefully add a batch of onions to the oil. Do not overcrowd the pot, as this will drop the temperature and lead to greasy onions.
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9
Fry the onions for 3-5 minutes, stirring constantly with a slotted spoon or spider skimmer to ensure even browning and to prevent them from clumping.
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10
Watch closely as they turn from pale yellow to a light golden brown. Remove them just before they reach your desired darkness, as they will continue to darken slightly from residual heat.
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11
Transfer the onions immediately to a baking sheet lined with several layers of paper towels. Spread them out into a single layer.
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12
While still hot, sprinkle with an extra pinch of sea salt. Allow them to cool completely at room temperature; they will become significantly crunchier as they cool.
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13
Repeat the process with the remaining onions, ensuring the oil returns to 160°C (320°F) between batches.
💡 Chef's Tips
Use a mandoline for perfectly even slices to ensure they all finish cooking at the same time. Maintain a steady oil temperature; if the oil is too hot, the onions will burn and turn bitter; if too cool, they will absorb oil and be soggy. Don't skip the cornstarch, as it provides a glass-like crunch that flour alone cannot achieve. Store cooled onions in an airtight container with a piece of paper towel to absorb any moisture; they will stay fresh for up to 2 weeks. If they lose their crunch after storage, refresh them in a 150°C (300°F) oven for 3-5 minutes.
🍽️ Serving Suggestions
Top a classic 'Varmkorv' (Swedish hot dog) with mashed potatoes, shrimp salad, and a generous handful of these onions. Sprinkle over Danish 'Hakkebøf' (minced beef patties with onions) for a modern textural contrast. Add a crunchy layer to 'Smørrebrød' featuring roast beef and remoulade. Fold into mashed potatoes (Potatismos) for a savory, textured side dish. Pair with a crisp Scandinavian Pilsner or a chilled glass of Aquavit.