In medium bowl, combine chicken, onions and taco seasoning mix; mix well.
For each serving, place 1 soft taco shell on microwave-safe plate. Spread with 1 tablespoon picante. Top with 1/4 cup chicken mixture and 2 tablespoons cheese. Repeat layers 2 more times.
Microwave 1 serving at a time on HIGH for 2 1/2 to 3 minutes or until cheese is melted, rotating plate 1/4 turn after 1 1/2 minutes. Cut into wedges; serve immediately.