Cook orzo as directed on package; drain. Rinse with cold water to cool; drain well.
Meanwhile, in large bowl, combine chicken, cheese, basil, pesto and salt; stir gently to mix. Add cooked orzo to chicken mixture; toss gently to coat. Sprinkle with lemon juice.
To make tomato cups, cut off stem end of tomato and scoop out pulp; discard. Spoon salad mixture into tomato cups. If desired, serve on lettuce-lined plates.