Best Corned Beef and Cabbage Recipe - Oven-Roasted

Ingredients

• 1 (4-lb) flat-cut corned beef with seasoning packet (do not trim the fat)
• 4 tablespoons unsalted butter, (melted)
• 2 tablespoons prepared horseradish
• 1½ teaspoons salt
• ¼ teaspoon ground black pepper
• 6 medium carrots, (cut into 2-in (5-cm) chunks)
• 1¼ lb small gold potatoes, (about 2.5-in (6.5-cm) diameter, halved)
• 1 very small green cabbage (cored and cut into ½-in (13-mm)-thick slices (see note))
• 2 tablespoons chopped Italian parsley, (for garnish (optional))
• 1 cup sour cream
• 2 tablespoons prepared horseradish, (plus more to taste)
• 1 tablespoon Dijon mustard
• 1 teaspoon white wine vinegar
• ¼ teaspoon salt
• ¼ teaspoon freshly ground black pepper
• ¼ teaspoon sugar