INGREDIENTS
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uncooked corned beef brisket (about 1 small), rinsed, trimmed if fatty, spice packet discarded if included
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sprigs flat-leaf parsley
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bay leaves, torn
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black peppercorns
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coriander seeds
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yellow mustard seeds
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medium onion, peeled, halved through root
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large russet potato, peeled, halved crosswise
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chopped fresh flat-leaf parsley, plus more for serving
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Kosher salt and freshly ground black pepper
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unsalted butter
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distilled white vinegar
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large eggs
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Chopped fresh chives (for serving)