To prepare vinaigrette, combine first 8 ingredients in a jar; cover tightly, and shake vigorously. Chill.
To prepare salad, steam green beans, covered, 3 minutes or until tender, and chill. Combine green beans, onion slices, orange slices, and grape halves in a large bowl. Drizzle vinaigrette over salad, tossing gently to coat.
