📝 About This Recipe
A centerpiece of German festive traditions, Karpfen Blau is a culinary marvel known for its striking, naturally iridescent blue skin. This delicate poaching method preserves the fish's tender, sweet flesh while infusing it with a sophisticated bouquet of root vegetables and aromatic spices. Served with a rich, frothy melted butter and fresh horseradish, it represents the pinnacle of old-world European elegance and clean, refined flavors.
🥗 Ingredients
The Fish
- 2 - 2.5 kg Fresh Mirror Carp (whole, gutted, with scales intact and slime layer preserved)
- 250 ml White Wine Vinegar (heated to near boiling to achieve the 'blue' effect)
The Poaching Liquid (Sud)
- 3 liters Water (or enough to fully submerge the fish)
- 500 ml Dry White Wine (Riesling or Müller-Thurgau recommended)
- 2 pieces Carrots (peeled and sliced into rounds)
- 1 stalk Leek (white and light green parts only, sliced)
- 100 g Celery Root (Celeriac) (peeled and diced)
- 1 large Onion (peeled and halved)
- 10 pieces Black Peppercorns (whole)
- 4 pieces Allspice Berries (whole)
- 3 pieces Juniper Berries (lightly crushed)
- 2 pieces Bay Leaves (dried)
- 2 tablespoons Salt (to season the poaching liquid)
For Serving
- 150 g Unsalted Butter (melted and slightly browned)
- 50 g Fresh Horseradish (finely grated)
- 1 piece Lemon (cut into wedges)
- 1/2 bunch Fresh Parsley (finely chopped)
👨🍳 Instructions
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1
Begin by preparing the poaching liquid (Sud). In a large fish kettle or a deep roasting pan wide enough for the whole fish, combine the water, white wine, carrots, leek, celery root, onion, peppercorns, allspice, juniper berries, bay leaves, and salt.
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2
Bring the liquid to a rolling boil, then reduce the heat and simmer gently for 20 minutes to allow the aromatics to infuse the water.
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3
While the broth simmers, prepare the carp. Handle the fish with extreme care; do not touch the skin more than necessary, as the natural slime layer is what reacts with vinegar to turn blue.
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4
Place the cleaned carp on a wire rack over a tray. Heat the 250ml of white wine vinegar in a small saucepan until it is steaming hot but not boiling.
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5
Slowly and evenly pour the hot vinegar over the entire fish. You will witness a magical transformation as the skin turns a beautiful, pale matte blue.
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6
Carefully lower the blue-tinted carp into the simmering poaching liquid. The fish should be fully submerged. If using a fish kettle, use the insert to lower it gently.
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7
Immediately reduce the heat to a bare simmer (about 80-85°C/175-185°F). The liquid should barely tremble; never let it boil, or the delicate skin will tear.
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8
Poach the carp for 20-25 minutes. A good indicator of doneness is when the dorsal fin can be easily pulled out.
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9
While the fish poaches, melt the butter in a small saucepan over medium heat. Let it foam and cook until it smells nutty and turns a light golden brown (beurre noisette).
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10
Prepare the garnishes: grate the fresh horseradish and chop the parsley. Slice the lemon into decorative wedges.
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11
Once cooked, carefully lift the carp out of the liquid using the kettle insert or two large spatulas. Drain briefly but work quickly to keep it warm.
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12
Place the whole fish on a warmed serving platter. Surround it with some of the cooked carrots and leeks from the poaching liquid for a rustic touch.
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13
Drizzle a small amount of the melted butter over the fish to give it a sheen, and serve the remaining butter in a sauceboat on the side.
💡 Chef's Tips
The most critical tip: Do not wash the fish under running water or scrub it; the 'blue' color depends entirely on the intact mucosal layer of the skin. If your carp is too large for your pot, you can carefully bend it into a 'U' shape and tie the head to the tail with kitchen twine before poaching. Always use a very fresh carp, ideally sourced from a local pond or trusted fishmonger on the day of cooking. To prevent the fish from sticking to the bottom, you can lay a few sprigs of parsley or extra leek slices on the rack before placing the fish down.
🍽️ Serving Suggestions
Serve with boiled 'Salzkartoffeln' (salted potatoes) tossed in parsley to soak up the delicious butter. A side of creamy cucumber salad with dill provides a refreshing contrast to the rich carp. Pair with a crisp, dry German Riesling from the Mosel or Rheingau region. Offer plenty of extra fresh-grated horseradish for those who enjoy a spicy kick to cut through the fat.