To prepare the vegan chocolate truffles start melting both the chocolates in a large heatproof bowl over a pan of simmering (not boiling) water.
Stir in the lemon zest, soya cream and coconut oil and mix until smooth.
Cover and chill for 2 hours.
Sift the cocoa powder onto a plate.
Roll teaspoons of the mixture into small balls between your hands.
Roll in the cocoa and put onto a plate.
Chill the vegan chocolate truffles for 1 hour before serving.