Corned Beef Hash

Ingredients

• 2 pounds uncooked corned beef brisket (about 1 small), rinsed, trimmed if fatty, spice packet discarded if included
• 4 sprigs flat-leaf parsley
• 3 bay leaves, torn
• 1 tablespoon black peppercorns
• 1 tablespoon coriander seeds
• 1 tablespoon yellow mustard seeds
• 1 medium onion, peeled, halved through root
• 1 large russet potato, peeled, halved crosswise
• 1/4 cup chopped fresh flat-leaf parsley, plus more for serving
• Kosher salt, freshly ground pepper
• 4 tablespoons unsalted butter
• 1 teaspoon distilled white vinegar
• 4 large eggs
• Chopped fresh chives (for serving)