6tablespoonSalted ButterChilled and cut into pieces.
Blue or Purple food colouringOptional
In a small food processor, blitz together blueberries and water.
Press blueberry pulp through a wire strainer, discarding the solids left behind. Set pulp aside.
In a small pot, whisk together egg yolks, large egg, and sugar until well combined. Add the blueberry pulp and the citric acid, whisk until well combined.
Cook over medium heat, whisking constantly, until mixture thickens. It should be able to coat the back of a spoon and retain a clear trail when a finger is dragged across the back of the spoon. Ideally, you want the mixture to reach 165F - I use an infrared surface thermometer for this.
Once mixture is thick / hot enough, transfer to a bowl. Add the pieces of butter, whisking until well incorporated.
Once all of the butter has melted in and been fully incorporated into the curd, tint blue or purple with food colouring, if desired (We added just a small amount of purple, hence the pale colour!)
Transfer blueberry curd to your storage container and chill for at least 1 hour before use.
This blueberry curd will last for 2 weeks in the fridge, or a few months in the freezer. (Thaw overnight in the fridge before use!)