Combine ranch dressing, sour cream, 1 teaspoon taco seasoning, and salsa in a small bowl. Cover and refrigerate until serving.
Toss chicken with remaining taco seasoning. Cover bowl loosely with wax paper or plastic wrap. Microwave chicken until chicken is heated through, about 2 to 3 minutes.
Warm the tortillas in a skillet for about a minute on each side to make them pliable. Place a scoop of chicken on the tortilla and top with lettuce, tomato, green onion, olives, avocado, cheese, and a spoonful of the ranch dressing mixture.