Generously season the brisket on both sides with the dry rub. In the pressure cooker, combine the molasses, vinegar, Worcestershire sauce, barbecue sauce, water, and Tabasco. Add the seasoned brisket on top.
Lock the lid in place, bring it to HIGH pressure and cook for 25 minutes. Release the pressure and flip the brisket over.
Lock the lid in place again, bring it to HIGH pressure and cook for 20 more minutes.
Remove the brisket to a platter and slice on the diagonal to serve. If desired, boil some of the water out of the juices remaining in the cooker and pour them over the meat before serving.