The steps are very much the same. First sear your brisket in a hot pan, remove and caramelize the onions as directed. You can combine all the sauce ingredients, onions and herbs in your slow cooker and add in the brisket. Cook, covered, on low, for 7 to 8 hours. When you're ready to build you sauce, you'll find it easiest to use a cornstarch slurry for the slow cooker.