In a small bowl, combine the remaining 3/4 cup of olive oil with the lemon juice, lemon zest, 2 tablespoons of salt and 2 teaspoons of pepper. Return the couscous to the bowls and toss with the dressing. Add the remaining ingredients; toss well. Slice the chicken crosswise 1/2 inch thick. Serve the couscous on platters, topped with the chicken.