Puree and strain the fruit.
measure out 1 cup (250 mL).
Whip the cream to a soft peak, stir in the vanilla, and chill until ready to assemble.
Stir the gelatin into ¼ cup (60 mL) of cool water in a small dish and set aside.
In a large metal bowl, whisk the egg yolks, whole egg, sugar and lemon juice together.
Place the bowl over a pot of gently simmering water and whisk constantly and rather vigorously (or you can use electric beaters) until they are frothy and doubled in volume, and registers 175 ºF (80 ºC).
Remove the bowl from the heat and whisk in the softened gelatin (the mixture will go fluid).
Whisk in the fruit puree – this will cool down the mixture, but make sure it has cooled to room temperature before folding in the whipped cream in 2 additions.
Pour the mousse into the pan and spread to level if needed (the mousse will be somewhat fluid at this point).
Chill the mousse for at least 6 hours before unmolding (this can be done a day ahead of serving.