1In a 6-qt. slow cooker, combine onions and lemons. Sprinkle brisket with Worcestershire sauce and steak seasoning.
Place brisket in slow cooker. If necessary, cut brisket to fit. Sprinkle with beef onion soup mix.
2In a medium bowl, whisk together bbq sauce, tea and honey mustard; pour over brisket in slow cooker.
Cover and cook on LOW for 8-10 hours.
3Transfer brisket to a cutting board and let rest for 10 minutes before slicing.
Strain sauce through a sieve and serve with brisket.