How to Make It
Combine first 9 ingredients (through garlic) in a medium bowl, stirring well to combine. Rub mixture into brisket.
Arrange tomatoes, onion, bell pepper, and jalapeño in the bottom of a 6-quart slow cooker. Place the brisket on top of vegetables, and drizzle any remaining spice mixture over brisket and vegetables. Cover and cook on LOW for 8 hours.
Remove the brisket from the slow cooker, and shred meat with 2 forks. Return brisket to cooker, and toss with the vegetables.