1. Heat the soy milk and coconut milk in a double boiler (you can use a metal bowl on top of a pot of boiling water). Bring almost to the boiling point.
2. Meanwhile, break the chocolate into small pieces and place in a large bowl.
3. Once the “milk” is boiling, check that no skin has developed on top of it. If it has, gently remove with a strainer. Pour hot milk over chocolate and whisk vigorously for about five minutes, until all chocolate is melted and smooth, and then whisk some more. Cover well and refrigerate 24 hours.
4. Scoop with a melon baller or a half-teaspoon measuring spoon and then use another measuring spoon of the same size to remove the chocolate from the first spoon. Roll between the palms of your hands to create evenly sized balls. After shaping each ball, immediately place in a small bowl of cocoa, toasted ground hazelnuts or coconut. Without touching the ball in your hands, move the bowl back and forth until the chocolate truffle is fully coated.
5. Remove gently and place on a flat tray. Place in refrigerator and refrigerate until 10 minutes before serving. Serve slightly chilled.