In 10-inch nonstick skillet, heat oil over medium-high heat. Add chicken; cook 3 to 5 minutes on first side, without moving, until chicken is browned on bottom and releases easily from pan. Stir chicken; stir in taco seasoning mix and water. Heat to simmering. Reduce heat to medium; cook uncovered 3 to 5 minutes, stirring occasionally, until sauce thickens and chicken is no longer pink in center.