Slow Cooked Corned Beef with Cabbage, Carrots, and Roasted Potatoes - ioanacooks

Ingredients

• 4 lb corned beef brisket, flat cut
• 1 tablespoon whole grain mustard
• 4 cups low-sodium beef broth
• 1 large onion, thickly sliced
• 4 garlic cloves, smashed
• 1 tablespoon whole peppercorns
• 2 bay leaves
• 4 sprigs fresh thyme
• 6 medium carrots, peeled and cut into chunks
• 1 head green cabbage, cored and sliced
• 2 tablespoons unsalted butter
• Kosher salt, to taste
• 1 1/2 lb red potatoes, halved
• 2 tablespoons canola oil
• Fresh parsley or chives, chopped, for garnish
• Prepared horseradish sauce, for serving