Mix the vinegars, garlic and water with salad dressing mix and oil. divide dressing in half. toss chicken in half of dressing until well coated and marinate for 2 hours or overnight. drain chicken, discarding marinade. Heat skillet over high heat. stir fry chicken 4-5 minutes or until no longer pink. add mushrooms and stir fry for 1 minute. serve over salad greens and top with remaining dressing, tomatoes and cheese.