1 head green cabbage, cut into wedges, rinsed and drained
Sauce:
Liquid from cooked corned beef mixture strained into a saucepan
2 tablespoons grainy mustard
1 teaspoon horseradish
1 tablespoon cornstarch + 2 tablespoon water
Instructions
Rinse corned beef under cold water and pat dry. Place in crock-pot.
In small bowl, combine yellow mustard, seasoning packet, salt and pepper. Spread evenly over corned beef. Sprinkle with brown sugar. Carefully pour Guinness around corned beef.
Place onions, potatoes, and carrots around beef and cook on low for 8 hours.
Remove vegetables and beef; tent with foil to keep warm. Add cabbage to liquid in crock-pot and cook on high for 1 hour. Remove cabbage and set aside.
To prepare sauce, strain remaining liquid into a saucepan. Simmer liquid for about 10 minutes to reduce down by ⅓. Add grainy mustard and horseradish. In small bowl, stir together cornstarch and water. Add to broth mixture slowly, stirring constantly to avoid lumps. Cook and stir until thickened. Serve over meat and vegetables.