In small bowl, combine ingredients for dressing. Mix until thoroughly blended and chill in refrigerator.
Heat broiler. Lightly spray rack of broiler pan with cooking spray. Place oats, cheese and cumin in blender container or food processor bowl; cover. Blend on high speed or process about 1 minute, stopping occasionally to stir; set aside. Pound each chicken breast half between sheets of waxed paper to 1/4-inch thickness. Spread mustard thinly over both sides of chicken; coat with oat mixture. Place chicken on broiler pan; spray one side of chicken evenly with cooking spray to coat completely, about 10 seconds. Broil about 6 inches from heat 3 to 4 minutes; remove pan from broiler. Turn chicken over; spray with cooking spray to coat, about 10 seconds. Broil an additional 3 to 4 minutes or until chicken is golden brown and no longer pink in center.
While chicken is cooking, combine salad greens, sliced onion and chopped herbs. When ready to serve, toss salad with dressing and place warm chicken over top. Serve with additional orange wedges and cilantro, if desired.