To make the blueberry vanilla compote, put all the ingredients in a medium pan and heat gently until the blueberries soften. Set aside for 5 minutes, then remove and discard the vanilla pod. Transfer to a serving dish.
To make the churros, sift together the flour and baking powder. Put the butter in a pan with 200ml cold water and a pinch of salt. Cook over a medium heat until the butter melts, then bring to the boil. Remove from the heat and add the flour. Beat with a wooden spoon until smooth.
Transfer to a bowl and leave to cool for 2 minutes. Gradually beat in the eggs until smooth. Stir in the orange zest, cover the bowl and set aside to rest for 30 minutes.
Pour enough oil into a large saucepan until one-third full. Place over a medium heat until the oil reaches 180°C. Spoon the batter into a piping bag fitted with a large star-shaped nozzle. Pipe 2 or 3 finger-length pieces directly into the oil, snipping off each with scissors. Cook for about 45 seconds each side, until golden. Remove with a slotted spoon, drain on kitchen paper and sprinkle with sugar. Repeat until all the batter is used. Serve with the compote.