In a food processor combine walnuts and 1/8 teaspoon salt. Cover and process with on/off pulses until finely chopped. Transfer to a shallow dish; set aside.
In the food processor combine dates, cocoa powder, apple juice, and 1/4 teaspoon salt. Cover and process until mixture forms a thick paste. If necessary, add 3 to 4 teaspoons water, 1 teaspoon at a time, to reach desired consistency.
Using 2 teaspoons of the dough for each truffle, shape into a ball. Roll balls in walnuts to coat. (If dough becomes too sticky, chill for 15 to 20 minutes). Cover and chill for at least 1 hour before serving. Store in an airtight container in the refrigerator for up to 2 weeks.