Pour the cream into a heavy-based saucepan. Scrape the tiny seeds out of the vanilla pod into the cream, then add the pod too, together with the orange zest. Heat until bubbles start to form round the edge of the pan, then remove from the heat, cover the pan and set aside to infuse for 20 minutes.
Meanwhile, whisk the egg yolks with 70 g of the sugar until thick and a pale lemon colour.
Pour the hot cream mixture into the yolks, stirring to mix. Return the mixture to the saucepan. Set over a low heat and cook, stirring constantly, for 5-10 minutes or until thickened - you should be able to run your finger across the custard on the back of the spoon and leave a clear trail - and bubbles just start to appear round the edge of the pan. Do not allow the custard to boil. (If you have an instant-read thermometer, you can check to be sure the custard has reached a temperature high enough to kill any bacteria that might be present in the eggs-81°C.)
Immediately remove from the heat and strain the custard into a jug, pressing all the vanilla seeds through the sieve. Divide the custard among 6-8 ramekins. Allow to cool, then cover and chill overnight to set.
Peel the oranges and cut out the segments from the surrounding membrane. Set the segments aside.
About 30 minutes before serving, sprinkle the remaining sugar over the custard (1 tablespoon to each ramekin), spreading it gently with your finger to make an even layer. Using a blowtorch, melt the sugar and caramelize it to a rich golden brown. Keep the flame moving, as the sugar will bubble up and then change colour. Leave to cool and set.
Set a ramekin on each plate and arrange the orange segments next to it. Add a tuile or two to each plate and serve.