1 vanilla pod, split in half lengthways and seeds scraped out
Mix the cream with the lemongrass in a pan, then bring to a simmer over a medium heat. Pour into a bowl, cover and infuse in the fridge for 6 hrs.
Heat oven to 120C/100C fan/gas ½. Whisk the sugar with the egg yolks. Warm the lemongrass cream to 50C, strain through a sieve, then whisk it into the egg mixture, along with the vanilla seeds. Pour the mixture into six ramekins.
Put the ramekins in a roasting tin and pour in hot water to halfway up their outside. Bake for 1 hr-1 hr 15 mins until set with a slight wobble. Remove the ramekins from the tin, cool to room temperature, then chill in the fridge for at least 3 hrs. Before serving, sprinkle some sugar over each ramekin and caramelise with a blowtorch until golden brown.