The night before serving, prepare rub for beef ribs (salt, pepper, seasoned garlic salt and optional cayenne pepper). Sprinkle both sides of ribs and then rub vigorously. Wrap in plastic wrap and refrigerate overnight.
In the morning, place on medium temperature grill and spread yellow mustard and brown sugar on each side of the ribs. Grill for 5-8 minutes until each side is slightly browned and caramelized.
Remove ribs from grill and slice with sharp knife. Place individual ribs in a Crock Pot on low. Add one bottle of your favorite barbeque sauce. Let simmer 6-8 hours.