Meanwhile brush chicken with oil and sprinkle with lemon pepper seasoning.
When grill is heated, place chicken on bottom grill surface; close grill. Cook 5-7 minutes or until chicken is fork tender and juices run clear. Remove chicken from grill, place on cutting board.
Meanwhile in large bowl, mix lettuce, strawberries and avocado. In small bowl, stir together sour cream and lemonade concentrate. pour half of sour cream mixture over lettuce mixture and toss to coat. Place on serving plates.
Slice chicken; arrange on salads. Drizzle with remaining sour cream mixture.