1.Preheat oven to moderately slow (170°C/150°C fan-forced). Make crostini. Discard the ends of the bread and slice into 2 centimetre thick pieces. Bake until lightly crispy.
2.Meanwhile, cut green section of onions into 8cm pieces; slice each piece lengthways into 12 thin strips (reserve white bulb sections of onions for another use). Place green onion strips in small bowl of iced water; refrigerate about 20 minutes or until curled.
3.Top crostini with duck, cucumber, sauce and onion curls. Serve immediately.