Place dates, walnuts, lemon juice, and ginger root in a food processor. Cover and process for 1 to 2 minutes or until well combined and sticky. Add chia seeds; pulse to combine.

Shape mixture into 1-inch balls. Place balls on baking sheet and set aside. Combine lemon zest and crystalized ginger in a small, shallow bowl. Roll each ball in mixture to coat evenly, gently pressing to adhere. Garnish with lemon slices, if desired. Store in an airtight container in the refrigerator up to 1 week.