Rinse the black beans thoroughly. Pour boiling water over them, allow to sit for two minutes, then drain again - this removes any strong bean flavour.
Add all ingredients to a high speed blender and blend for 3 to 5 minutes, until completely smooth and creamy.
Pour into a shallow freezer safe container and cover.
Freeze for 60 to 90 minutes, until the edges are set but the centre is still soft. Whisk firmly once to break up ice crystals and smooth the mixture.
Return to the freezer and freeze until set, around 3 to 4 hours.
Allow to sit at room temperature for 5-10 minutes before scooping.