Combine 2 tablespoons green onions and next 4 ingredients in container of an electric blender; cover and process until smooth. Brush both sides of chicken breast halves with green onion mixture.
Coat grill rack with cooking spray; place over medium-hot coals (350° to 400°). Place chicken on rack, and grill, covered, 5 minutes on each side or until done. Cut chicken crosswise into 1/4-inch-thick strips.
Place 2 cups salad greens on each individual serving plate; top with mango and remaining green onions. Arrange chicken over salads; top each serving with 3 tablespoons dressing.