Spray 5- to 6-quart slow cooker with cooking spray. In cooker, place potatoes, carrots and onion. Top with corned beef; sprinkle with contents of seasoning packet. Add beer and enough water to just cover corned beef.
Cover; cook on Low heat setting 10 to 12 hours.
Remove corned beef from cooker; place on serving platter and cover to keep warm. Add cabbage wedges to vegetables and broth in cooker. Increase heat setting to High. Cover; cook 30 to 35 minutes longer or until cabbage is crisp-tender.
Meanwhile, in small bowl, mix sauce ingredients.
To serve, cut corned beef across grain into thin slices. With slotted spoon, remove vegetables from cooker. If desired, skim fat from juices in cooker. Serve vegetables with juices and corned beef with sauce.