Chop or break the bar of chocolate into small pieces.
Place a heatproof bowl over a saucepan of boiling water, add the chocolate to the bowl and stir until melted.
Take the bowl off the heat, and stir in the coconut oil until combined.
Add the orange juice, orange zest, icing sugar and cocoa powder and stir until completely smooth.
Chill the mixture in the fridge until it has become solid enough to shape with your hands. It's usually ready in 15-25 minutes, but I like to check on it regularly to get the perfect time to roll the truffles.
With a small spoon, scoop out portions of the dough and then roll them into balls between the palms of your hands. If your hands are warm, covering your palms in cocoa powder before rolling will reduce melting. If the mix is very sticky, you may want to chill it for a little longer.
Sprinkle some cocoa powder on a plate, and then roll the balls in the cocoa until they are evenly coated.
Store in an airtight container and serve at room temperature.
For variation, you can roll these truffles in coconut, or finely chopped nuts. For an boozy twist, try our Rum Truffles.