Ingredients

• 4 pounds corned beef brisket, or more to taste
• water to cover
• 1 medium head cabbage, cored and cut into 6 wedges
• 12 small red potatoes, halved
• 1 pound small white onions, peeled
• 6 large carrots, peeled and cut in chunks
• Sauce:
• 1 tablespoon unsalted butter
• 2 tablespoons all-purpose flour
• 1 tablespoon red wine vinegar
• 1/2 cup reduced-fat sour cream
• 2 tablespoons coarse Dijon mustard

Instructions

1. Place corned beef in a 6-quart Dutch oven or heavy pot and pour in enough water to cover beef by 2 inches. Bring water to a boil, skimming the liquid occasionally to remove fat from top. Reduce heat to medium-low, cover Dutch oven with a lid, and simmer for 2 hours.
2. Arrange cabbage, potatoes, onions, and carrots around beef and return liquid to a boil. Lower heat to medium-low, cover Dutch oven, and simmer until vegetables are tender, about 40 minutes. Transfer beef to a serving platter, reserving 1 1/2 cups cooking liquid. Surround meat with the vegetables.
3. Melt butter in a small saucepan over medium heat. Whisk flour into melted butter until dissolved and bubbling, about 1 minute. Add reserved cooking liquid and vinegar to butter-flour mixture; cook, stirring frequently, until sauce is slightly thickened, about 4 minutes. Remove saucepan from heat and whisk sour cream and mustard into sauce. Serve sauce alongside corned beef and vegetables.