Stir the soup, water, chili powder, brown sugar, cumin and cinnamon in a 6-quart slow cooker. Add the pork and turn to coat.
Cover and cook on LOW for 8 to 9 hours or until the pork is fork-tender. Remove the pork to a cutting board. Using 2 forks, shred the pork. Add the chocolate to the cooker and stir until melted. Return the pork to the cooker.
Place about 1/2 cup pork mixture onto half of each tortilla. Top with the tomatoes and cilantro. Fold the tortillas over the filling.