With sharp knife, cut each thigh in half; remove bone and skin. Place in crockpot. Combine enchilada sauce mix with tomato paste and water. Mixture will be thick. Spread on thighs. Cover; cook on Low 7 to 8 hours or until tender.
Turn pot on High. Add cheese; stir until melted. Spoon into an au gratin dish or shallow casserole. Spoon yogurt over turkey. Sprinkle with onions. Top with corn chips.