1. Prepare rice according to package directions. Fluff with a fork & set aside.
2. In a small bowl, mix black & cayenne pepper. Coat chicken with pepper mixture.
3. In a large skillet, heat oil over medium. Add chicken & cook 10-12 minutes per side, or until browned on outside & done throughout.
4. Meanwhile, in a medium bowl mix onion, tomato & lime juice. Set aside.
5. Just before serving, stir avocado into onion mixture. Serve chicken over rice & topped with salsa.