Place ribs on a rack fitted a broiler pan. Place pan in broiler, 6 inches from heat. Broil the ribs for 10 minutes or until well browned, turning once.
While the ribs are broiling, place the vegetables in the bottom of your slow cooker.
When the ribs are ready, place them on top of the vegetables.
In a mixing bowl, add the beer, 6 tablespoons mustard, 2 tablespoons of Worcestershire sauce, mix together. Pour mixture over the ribs. Cover the slow cooker and set to High setting and cook for 5 hours or until the meat is tender.
Transfer the meat and vegetables to a platter, keep warm.
Strain the fat from the slow cooker then pour the broth into a saucepan.
In a measuring cup, mix together the cornstarch and 2 tablespoons of cold water. Stir into the broth, then stir in the remaining 2 tablespoons of mustard and 1 tablespoon of Worcestershire sauce.
Place on heat and bring to a boil, stirring often. Reduce heat to low and cook gravy, stirring often, for 2 minutes or until thickened.
Serve meat and vegetables with the gravy, and have additional mustard available for the meat, as desired. Enjoy.