Put the cream and the vanilla in a saucepan and simmer until steaming.
Whisk the egg yolks and sugar together until pale and fluffy.
Carefully 'temper' the cream mixture into the egg yolks by adding a little, then adding the rest, whisking all the time. Pour back into the pan and continue to stir until you can draw a line in the custard on the spoon.
Preheat the oven to 120ºC.
Add the persimon and salt to the mixture.
Pour the mixture into the ramekins in the baking tray. Boil a kettle.
Fill the baking tray until halfway up the ramekins with hot water.
Bake for 40 minutes. Remove from the oven and leave to cool. Place in the fridge overnight.
Place a fan of persimon fruit on top and serve.