Preheat oven to 190°C and line a 20cm springform tin and two baking sheets with parchment.
Whisk egg yolks and half the sugar until thick and pale, then fold in vanilla, flour, cornflour, and salt.
Whisk egg whites with cream of tartar and remaining sugar to form a glossy meringue.
Fold meringue into the yolk mixture in batches and pipe 11cm lines onto baking sheets.
Dust with icing sugar and bake for 10-12 minutes until slightly spongy, then cool on a wire rack.
Heat milk and whisk into egg yolks and sugar, then stir in soaked gelatine and cook until thickened.
Transfer custard to a bowl and stir in the passion fruit purée, then leave to cool.
Whip the double cream to soft peaks and fold into the cooled passion fruit mixture.
Line the tin with upright savoiardi biscuits, fill with bavarois, and chill for 4 hours.
Boil lime juice, zest, sugar, and 150ml water together until the sugar dissolves.
Stir in gelatine and green coloring, cool until slightly set, then pour over the bavarois and chill for 4 hours.
Remove from the tin and decorate with fresh fruit to serve.