• Stir sugar & water together in small saucepan over medium heat until sugar is dissolved. Scrape seeds from vanilla bean into pan, add bean too. Boil gently, without stirring, for about 3 minutes until thickened slightly. Remove from heat & pour into medium bowl.
• Add blueberries & orange & stir to coat. Cover & refrigerate for 6 hours or overnight if time permits; remove vanilla bean just before serving.

To make the zabaglione:

• combine the yolks and sugar in a medium, heatproof bowl. Using an electric, beat for 3 to 4 minutes or until the mixture is thick, pale & doubled in volume. Place the bowl over a small saucepan of simmering water, ensuring that the bottom of the bowl is not sitting in the water. Whisk the mixture, adding 2 teaspoons of the liqueur at a time until all the liqueur is added & the mixture is thick, grown in volume & leaves a trail when the whisk is dragged through it. Serve immediately.
• To serve, give the blueberry mixture a good stir & spoon spoon into individual serving glasses or dishes along with some of the juice. Drizzle with the zabaglione & serve immediately. Serves 4 to 6.