Rub chicken with olive oil and season both sides with salt and pepper. Grill chicken over medium-high heat 10-15 minutes, turning once until chicken registers 165F. Allow chicken to cool then cut into cubes.
In a large bowl, combine orzo, chicken, tomatoes, mozzarella, and basil. In a separate small bowl, whisk dressing ingredients until smooth and then pour over orzo. Stir until coated and season pasta with salt and pepper to taste. Chill until ready to serve. Enjoy!