1. Coat the inside of a slow cooker with cooking spray. Combine cornstarch and soy sauce in cooker until cornstarch is dissolved; add vinegar, honey, hoisin sauce, ginger and orange juice. Add chicken and cook on low 8 hours.
2. Transfer chicken to cutting board, shred and return to sauce. Place cucumber on bottom half of each roll; top with chicken mixture, radishes and other half of roll.