Season chicken with black pepper and arrange on baking sheet. Bake until chicken is thoroughly cooked, about 25 minutes. Cool, then cut into bite-size pieces.
Combine cooked chicken, rice, celery, green onions, water chestnuts, red pepper and almonds; set aside.
Combine Hellmann's® Real Mayonnaise, soy sauce, Maille Dijon Mustard, vinegar, lemon juice and sesame seed oil in small bowl with wire whisk. Pour over chicken and vegetables; toss. Garnish, if desired, with mandarin oranges.