Place chicken in slow cooker and sprinkle with pepper. Mix all other ingredients together, except cornstarch and water. Pour over chicken. Cover and cook on low for 7 to 9 hours, or high for 3 to 4 hours. Remove chicken and shred. Mix cornstarch and water together and add to sauce mixture. Cook on high with lid slightly ajar until sauce is thickened. Replace chicken. Serve over hot cooked rice.