Pour the apple juice into a shallow saucepan or frying pan with a lid. Add the caster sugar and brandy. Bring the mixture to a boil; reduce heat to medium.
Add the peaches and nectarines to pan. Cover and poach gently 2 minutes. If the skins come off, remove them from the pan. Add mangoes and poach another 2 minutes. Use a slotted spoon to transfer the fruit to a serving bowl.
Boil the juice mixture 5 to 10 minutes, or until reduced to a slightly heavy syrup. Pour over the fruit.
To make the sabayon sauce, beat egg yolks and caster sugar in top half of a double boiler over gently simmering water, 2 to 3 minutes, until creamy.
Beating continuously, add brandy in a thin, steady stream. Continue beating 10 to 12 minutes until sauce is thick. Pour into a jug and serve with poached fruit.
• You can beat the eggs for a sabayon with water, sweet white wine, champagne, brandy, rum or liqueur. This sauce is usually served warm and foaming. If you want to serve it cold, remove it from the heat after 3 minutes and continue beating for 10 to 12 minutes until creamy.
• For an elegant presentation, spoon the salad into individual ramekins and top with the sabayon. Put the ramekins under the broiler until the peaks of the sabayon sauce begin to brown.