Spray 1 1/2- to 2-quart slow cooker with cooking spray. In cooker, place onion and peppers. Top with beef. Sprinkle with chili powder, oregano, garlic and salt. Drizzle with lime juice. Add broth.
Cover; cook on Low heat setting 6 to 8 hours.
About 20 minutes before serving, cook rice as directed on package.
Remove beef from cooker; place on cutting board. Shred beef with 2 forks; return to cooker and mix well. Stir in black beans. Increase heat setting to High. Cover; cook about 5 minutes longer or until thoroughly heated. Serve beef and sauce over rice.