Cut each fish fillet into 1 1/2-inch-thick slices. Thread half of fish onto 2 skewers placed 2 inches apart. Repeat procedure with remaining fish, and place kabobs in a shallow dish.
Stir together dressing and next 4 ingredients. Pour over fish; add fresh herb sprigs, if desired. Cover and chill 30 minutes.
Remove fish from marinade, discarding marinade.
Grill, covered with grill lid, over high heat (400° to 500°) 4 minutes on each side or until fish reaches desired degree of doneness.