Place the first 9 ingredients in a blender; cover and process until smooth. Add broth; pulse to combine.
Place roast and bay leaves in a 4- or 5-qt. slow cooker; pour sauce over top. Cook, covered, on low until meat is tender, 7-9 hours.
Prepare rice about 30 minutes before serving. In a large saucepan, combine water, rice, butter and salt; bring to a boil. Reduce heat; simmer, covered, until liquid is absorbed and rice is tender, 12-15 minutes. Remove from heat; gently stir in cilantro and lime juice.
Remove roast from slow cooker; cool slightly. Discard bay leaves and skim fat from cooking juices. Shred beef with 2 forks; return to slow cooker. Serve with rice and, if desired, radishes, cilantro and limes.
