Break 1 egg into a large heatproof bowl. Separate the remaining egg, pouring the yolk into the first bowl and the eggwhite into a separate clean bowl. Add the third egg yolk and sugar to the first bowl. Whisk the egg and sugar mixture until it is pale and frothy, using an electric hand mixer.
Place the bowl over a saucepan of simmering water and continue to whisk for about 10 minutes, adding the wine a little at a time, until the mixture has tripled in volume and is warm to the touch. Do not allow the water in the pan to boil while you are whisking. Remove the bowl from the heat.
Sprinkle the gelatine into 2 tablespoons of hot (not boiling) water in a jug and stir briskly until thoroughly mixed. If it does not fully dissolve because the liquid has cooled, stand the jug in a saucepan of hot water and continue to stir until fully dissolved. Do not allow the gelatine mixture to boil.
Pour the dissolved gelatine into the egg mixture and whisk in. Sit the bowl over a saucepan of cold water and continue whisking for a further 5 minutes until the mixture is cold.
Whip the cream until lightly thickened and doubled in volume, then fold into the egg mixture. Whisk the egg white into stiff peaks in a clean bowl, then fold into the mixture. Spoon into six dessert glasses and refrigerate for 2 hours.
Just before serving, scatter the berries over the top of the desserts and decorate with sprigs of mint.