In a 3 1/2- or 4-quart slow cooker, place chicken. Drain 1 can of the tomatoes, chop tomatoes from both cans. Combine in a medium bowl the chopped tomatoes and the juice from 1 can of tomatoes, tapioca, ginger, cilantro, garlic, crushed red pepper, and salt. Pour over chicken in cooker.
Cover and cook on low-heat setting for 6 to 7 hours or on high-heat setting for 3 to 3 1/2 hours. Skim off fat. Serve in shallow bowls. Serve with hot cooked rice, (optional).